styles.css

:root {
  --bg-color: #ffffff;
  --editor-bg: #f6f8fa;
  --preview-bg: #ffffff; /* Preview background for light mode */
  --text-color: #24292e;
  --text-secondary: #57606a;
  --font-mono: ui-monospace, SFMono-Regular, SF Mono, Menlo, Consolas, Liberation Mono, monospace;
  --color-danger-fg: #d73a49;
  --preview-text-color: #24292e; /* Text color for preview in light mode */
  --border-color: #e1e4e8;
  --header-bg: #f6f8fa;
  --button-bg: #f6f8fa;
  --button-hover: #e1e4e8;
  --button-active: #d1d5da;
  --scrollbar-thumb: #c1c1c1;
  --scrollbar-track: #f1f1f1;
  --accent-color: #0366d6;
  --table-bg: #ffffff; /* Table background for light mode */
  --code-bg: #f6f8fa; /* Code block background for light mode */
  --skeleton-bg: #e2e8f0;
  --skeleton-glow: rgba(255, 255, 255, 0.65);

  /* Find & Replace Panel custom properties (PERF-010 consolidated) */
  --fr-bg: rgba(255, 255, 255, 0.95);
  --fr-border: #d0d7de;
  --fr-shadow: 0 8px 24px rgba(140, 149, 159, 0.2);
  --fr-btn-active: #0969da;
  --fr-btn-active-bg: #ddf4ff;
  --fr-match-highlight: #ffdf5d;
  --fr-match-active: #ff9b30;
  --fr-match-text-color: #24292e;
  --fr-match-active-text-color: #24292e;
  --fr-error-bg: #ffebe9;
  --fr-error-border: #ff8577;
  --fr-text-danger: #cf222e;
}

[data-theme="dark"] {
  --bg-color: #0d1117;
  --editor-bg: #161b22;
  --preview-bg: #0d1117; /* Preview background for dark mode */
  --text-color: #c9d1d9;
  --text-secondary: #8b949e;
  --color-danger-fg: #f85149;
  --preview-text-color: #c9d1d9; /* Text color for preview in dark mode */
  --border-color: #30363d;
  --header-bg: #161b22;
  --button-bg: #21262d;
  --button-hover: #30363d;
  --button-active: #3b434b;
  --scrollbar-thumb: #484f58;
  --scrollbar-track: #21262d;
  --accent-color: #58a6ff;
  --table-bg: #161b22; /* Table background for dark mode */
  --code-bg: #161b22; /* Code block background for dark mode */
  --skeleton-bg: #2d3139;
  --skeleton-glow: rgba(255, 255, 255, 0.08);

  /* Find & Replace Panel custom properties for dark mode */
  --fr-bg: rgba(28, 33, 40, 0.98);
  --fr-border: #444c56;
  --fr-shadow: 0 8px 24px rgba(0, 0, 0, 0.5);
  --fr-btn-active: #2f81f7;
  --fr-btn-active-bg: rgba(56, 139, 253, 0.15);
  --fr-match-highlight: rgba(187, 128, 9, 0.4);
  --fr-match-active: #ad6200;
  --fr-match-text-color: #c9d1d9;
  --fr-match-active-text-color: #ffffff;
  --fr-error-bg: rgba(248, 81, 73, 0.1);
  --fr-error-border: rgba(248, 81, 73, 0.4);
  --fr-text-danger: #ff7b72;
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

@media (min-width: 768px) {
  html,
  body {
    height: 100%;
    overflow: hidden;
  }
}

body {
  background-color: var(--bg-color);
  color: var(--text-color);
  /* PERF-021: Removed background-color transition to avoid full-viewport repaint on theme toggle */
  transition: color 0.15s ease;
  min-height: 100vh;
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Hiragino Kaku Gothic ProN", Meiryo, "Malgun Gothic", "Apple SD Gothic Neo", "Segoe UI", Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
}

.app-header {
  background-color: var(--header-bg);
  border-bottom: 1px solid var(--border-color);
  padding: 0.35rem 0.75rem;
  transition: background-color 0.3s ease;
  position: relative;
  z-index: 100;
  flex-shrink: 0;
}

.app-container {
  height: 100vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.content-container {
  display: flex;
  flex: 1;
  overflow: hidden;
}

.editor-pane, .preview-pane {
  flex: 1;
  padding: 20px;
  overflow-y: auto;
  position: relative;
  /* PERF-025: Shortened transition and scoped to background-color only */
  transition: background-color 0.15s ease;
}

.editor-pane {
  background-color: var(--editor-bg);
  border-right: 1px solid var(--border-color);
  padding-right: 0px;
  --line-number-gutter: 0px;
}

.preview-pane {
  background-color: var(--preview-bg); /* Using the new variable for preview background */
}

/* Custom scrollbar */
.editor-pane::-webkit-scrollbar,
.preview-pane::-webkit-scrollbar,
#markdown-editor::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

.editor-pane::-webkit-scrollbar-track,
.preview-pane::-webkit-scrollbar-track,
#markdown-editor::-webkit-scrollbar-track {
  background: var(--scrollbar-track);
}

.editor-pane::-webkit-scrollbar-thumb,
.preview-pane::-webkit-scrollbar-thumb,
#markdown-editor::-webkit-scrollbar-thumb {
  background: var(--scrollbar-thumb);
  border-radius: 4px;
}

.editor-pane::-webkit-scrollbar-thumb:hover,
.preview-pane::-webkit-scrollbar-thumb:hover,
#markdown-editor::-webkit-scrollbar-thumb:hover {
  background: var(--button-active);
}

#markdown-editor {
  width: 100%;
  height: 100%;
  border: none;
  background-color: transparent;
  color: var(--text-color);
  resize: none;
  font-family: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
  font-size: 14px;
  line-height: 1.5;
  padding: 10px;
  padding-left: calc(10px + var(--line-number-gutter));
  transition: background-color 0.3s ease, color 0.3s ease;
  overflow-y: auto;
  position: relative;
  z-index: 3;
}

#markdown-editor:focus {
  outline: none;
}

.preview-pane {
  padding: 20px;
}

.markdown-body {
  padding: 20px;
  width: 100%;
  background-color: var(--preview-bg); /* Ensuring the markdown content matches preview background */
  color: var(--preview-text-color); /* Using specific text color for preview content */
}

.markdown-body a.reference-link {
  font-size: 0.75em;
  letter-spacing: -0.02em;
  line-height: 1;
  vertical-align: super;
  position: relative;
  top: 0.08em;
}

/* Style tables in light mode */
.markdown-body table {
  background-color: var(--table-bg);
  border-color: var(--border-color);
}

.markdown-body table tr {
  background-color: var(--table-bg);
  border-top: 1px solid var(--border-color);
}

.markdown-body table tr:nth-child(2n) {
  background-color: var(--bg-color);
}

/* Style code blocks in light mode */
.markdown-body pre {
  background-color: var(--code-bg);
  border-radius: 6px;
}

.markdown-body code {
  background-color: var(--code-bg);
  border-radius: 3px;
  padding: 0.2em 0.4em;
}

.markdown-body img.emoji-inline {
  width: 1em;
  height: 1em;
  vertical-align: -0.1em;
}

.markdown-body ul,
.markdown-body ol {
  padding-left: 2em;
  margin: 0.4em 0;
}

.markdown-body ul ul,
.markdown-body ul ol,
.markdown-body ol ul,
.markdown-body ol ol {
  margin-top: 0.2em;
  margin-bottom: 0.2em;
}

.markdown-body ul.contains-task-list,
.markdown-body li.task-list-item {
  list-style: none;
}

.markdown-body ul.contains-task-list {
  padding-left: 2em;
}

.markdown-body li.task-list-item input[type="checkbox"] {
  margin: 0 0.5em 0.2em 0;
  vertical-align: middle;
  pointer-events: none;
}

.markdown-body li.task-list-item::marker {
  content: "";
}

.markdown-body li:has(> input[type="checkbox"]) {
  list-style: none;
}

.markdown-body li:has(> input[type="checkbox"])::marker {
  content: "";
}

.markdown-body ul:has(> li > input[type="checkbox"]) {
  list-style: none;
  padding-left: 2em;
}

.markdown-body .footnotes {
  margin-top: 1.5rem;
  font-size: 0.9em;
}

.markdown-body .footnotes ol {
  padding-left: 1.5em;
}

.markdown-body .footnotes ol > li::marker {
  content: "[" counter(list-item) "] ";
  font-weight: 600;
}

.markdown-body .footnotes li > p {
  margin: 0.2em 0;
}

.markdown-body .footnote-ref a,
.markdown-body .footnote-backref {
  text-decoration: none;
}

.markdown-body .footnote-backref {
  margin-left: 0.4em;
}

.markdown-body .markdown-alert {
  padding: 0.5rem 1rem;
  margin-bottom: 16px;
  border-left: 0.25em solid;
  border-radius: 0.375rem;
}

.markdown-body .markdown-alert > :last-child {
  margin-bottom: 0;
}

.markdown-body .markdown-alert-title {
  margin: 0 0 8px;
  font-weight: 600;
  line-height: 1.25;
  display: flex;
  align-items: center;
  gap: 8px;
}

.markdown-body .markdown-alert-icon {
  display: inline-flex;
  width: 16px;
  height: 16px;
}

.markdown-body .markdown-alert-icon svg {
  width: 16px;
  height: 16px;
  fill: currentColor;
}

.markdown-body .markdown-alert-note {
  color: #0969da;
  border-left-color: #0969da;
  background-color: #ddf4ff;
}

.markdown-body .markdown-alert-tip {
  color: #1a7f37;
  border-left-color: #1a7f37;
  background-color: #dafbe1;
}

.markdown-body .markdown-alert-important {
  color: #8250df;
  border-left-color: #8250df;
  background-color: #fbefff;
}

.markdown-body .markdown-alert-warning {
  color: #9a6700;
  border-left-color: #9a6700;
  background-color: #fff8c5;
}

.markdown-body .markdown-alert-caution {
  color: #cf222e;
  border-left-color: #cf222e;
  background-color: #ffebe9;
}

.markdown-body .markdown-alert > *:not(.markdown-alert-title) {
  color: var(--preview-text-color);
}

[data-theme="dark"] .markdown-body .markdown-alert-note {
  color: #4493f8;
  background-color: rgba(31, 111, 235, 0.15);
  border-left-color: #4493f8;
}

[data-theme="dark"] .markdown-body .markdown-alert-tip {
  color: #3fb950;
  background-color: rgba(35, 134, 54, 0.15);
  border-left-color: #3fb950;
}

[data-theme="dark"] .markdown-body .markdown-alert-important {
  color: #ab7df8;
  background-color: rgba(137, 87, 229, 0.15);
  border-left-color: #ab7df8;
}

[data-theme="dark"] .markdown-body .markdown-alert-warning {
  color: #d29922;
  background-color: rgba(210, 153, 34, 0.18);
  border-left-color: #d29922;
}

[data-theme="dark"] .markdown-body .markdown-alert-caution {
  color: #f85149;
  background-color: rgba(248, 81, 73, 0.18);
  border-left-color: #f85149;
}

.toolbar {
  display: flex;
  gap: 8px;
  align-items: center;
}

.toolbar-group {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.toolbar-divider {
  width: 1px;
  height: 20px;
  background-color: var(--border-color);
  opacity: 0.7;
}

.tool-button {
  background-color: var(--button-bg);
  border: 1px solid var(--border-color);
  color: var(--text-color);
  border-radius: 5px;
  padding: 4px 8px;
  font-size: 13px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 4px;
  /* PERF-016: Specific transition properties instead of 'all' to avoid animating layout-triggering properties */
  transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}

.tool-button:hover {
  background-color: var(--button-hover);
}

.tool-button:active {
  background-color: var(--button-active);
}

.tool-button:disabled,
.tool-button[aria-disabled="true"] {
  cursor: not-allowed;
  opacity: 0.5;
}

.tool-button i {
  font-size: 15px;
}

.tool-button.is-active,
.tool-button.is-active:hover {
  border-color: var(--accent-color);
  color: var(--accent-color);
  background-color: rgba(3, 102, 214, 0.08);
}

.btn-text {
  display: none;
}

.toolbar .tool-button {
  height: 28px;
  min-width: 28px;
}

.toolbar .tool-button.sync-active {
  border-color: var(--accent-color);
  color: var(--accent-color);
}

.file-input {
  display: none;
}

/* Drag overlay: full-screen drop target shown when user drags a file over the window */
.drag-overlay {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 9999;
  background-color: rgba(0, 0, 0, 0.45);
  pointer-events: none;
  align-items: center;
  justify-content: center;
}

.drag-overlay.active {
  display: flex;
  pointer-events: auto;
}

.drag-overlay-inner {
  border: 3px dashed var(--accent-color);
  border-radius: 12px;
  padding: 48px 64px;
  text-align: center;
  color: #ffffff;
  background-color: rgba(3, 102, 214, 0.15);
  animation: overlayPulse 1.4s ease-in-out infinite;
}

.drag-overlay-icon {
  display: block;
  font-size: 3rem;
  margin-bottom: 12px;
  color: var(--accent-color);
}

.drag-overlay-text {
  font-size: 1.4rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.drag-overlay-sub {
  font-size: 0.85rem;
  opacity: 0.75;
  margin-bottom: 0;
}

@keyframes overlayPulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.015); }
}

/* Editor drop hint: subtle text at bottom of editor pane, shown only when empty */
.drop-hint {
  position: absolute;
  bottom: 14px;
  left: 0;
  right: 0;
  text-align: center;
  font-size: 0.75rem;
  color: var(--text-color);
  opacity: 0.35;
  pointer-events: none;
  user-select: none;
  z-index: 3;
}

.editor-pane:has(#markdown-editor:not(:placeholder-shown)) .drop-hint {
  display: none;
}

.line-numbers {
  position: absolute;
  top: 20px;
  bottom: 20px;
  left: 20px;
  width: var(--line-number-gutter);
  padding: 10px 8px 10px 0;
  font-family: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
  font-size: 14px;
  line-height: 1.5;
  text-align: right;
  color: var(--text-secondary);
  background-color: var(--editor-bg);
  border-right: 1px solid var(--border-color);
  box-sizing: border-box;
  overflow: hidden;
  pointer-events: none;
  user-select: none;
  z-index: 2;
  font-variant-numeric: tabular-nums;
}

.line-numbers .line-number {
  display: block;
  height: auto;
}

.editor-highlight-layer {
  position: absolute;
  inset: 20px 0 20px calc(20px + var(--line-number-gutter));
  padding: 10px;
  font-family: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
  font-size: 14px;
  line-height: 1.5;
  white-space: pre-wrap;
  word-wrap: break-word;
  color: transparent;
  pointer-events: none;
  overflow: auto;
  background-color: var(--editor-bg);
  border-radius: 4px;
  z-index: 1;
}

.editor-highlight-layer::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

.editor-highlight-layer::-webkit-scrollbar-thumb {
  background: transparent;
}

.editor-highlight-layer::-webkit-scrollbar-track {
  background: transparent;
}

.find-highlight {
  background-color: var(--fr-match-highlight, rgba(255, 223, 93, 0.4)) !important;
  border-radius: 2px;
  color: transparent !important;
  padding: 0 !important;
  margin: 0 !important;
}

.find-highlight.active {
  background-color: var(--fr-match-active, #ff9b30) !important;
  color: transparent !important;
  padding: 0 !important;
  margin: 0 !important;
  outline: 1px solid var(--accent-color, #0366d6) !important;
  outline-offset: -1px;
}

.preview-find-highlight {
  background-color: var(--fr-match-highlight, rgba(255, 223, 93, 0.4)) !important;
  color: var(--fr-match-text-color, inherit) !important;
  border-radius: 2px;
  padding: 0 1px !important;
  margin: 0 !important;
}

.preview-find-highlight.active {
  background-color: var(--fr-match-active, #ff9b30) !important;
  color: var(--fr-match-active-text-color, inherit) !important;
  outline: 1px solid var(--accent-color, #0366d6) !important;
  outline-offset: -1px;
}

/* Dropdown improvements */
.dropdown-menu {
  background-color: var(--bg-color);
  border-color: var(--border-color);
}

.dropdown-item {
  color: var(--text-color);
}

.dropdown-item:hover, .dropdown-item:focus {
  background-color: var(--button-hover);
  color: var(--text-color);
}

/* Markdown formatting toolbar */
.markdown-format-toolbar {
  display: flex;
  align-items: center;
  height: 34px;
  padding: 0 6px;
  background-color: var(--header-bg);
  border-bottom: 1px solid var(--border-color);
  overflow-x: auto;
  overflow-y: hidden;
  flex-shrink: 0;
  scrollbar-width: none;
  -ms-overflow-style: none;
}

.markdown-format-toolbar::-webkit-scrollbar {
  display: none;
}

.markdown-toolbar-group {
  display: flex;
  align-items: center;
  gap: 2px;
  height: 100%;
  padding: 0 6px;
  border-right: 1px solid var(--border-color);
  flex-shrink: 0;
}

.markdown-toolbar-group:first-child {
  padding-left: 0;
}

.markdown-toolbar-group:last-child {
  border-right: none;
  padding-right: 0;
}

.markdown-tool-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 26px;
  border: 1px solid transparent;
  border-radius: 4px;
  background: transparent;
  color: var(--text-color);
  cursor: pointer;
  font-size: 14px;
  line-height: 1;
  padding: 0;
  transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}

.markdown-tool-btn:hover,
.markdown-tool-btn:focus-visible {
  background-color: var(--button-hover);
  border-color: var(--border-color);
  color: var(--accent-color);
}

.markdown-tool-btn:active {
  background-color: var(--button-active);
}

.markdown-tool-btn:disabled,
.markdown-tool-btn.disabled {
  opacity: 0.4;
  cursor: not-allowed;
  pointer-events: none;
}

.markdown-tool-btn i {
  font-size: 15px;
}

.markdown-tool-btn[data-md-action="reference"] i::before {
  content: "[ ]";
  font-style: normal;
  font-size: 12px;
  letter-spacing: -0.12em;
}

.markdown-tool-btn.text-tool {
  width: auto;
  min-width: 26px;
  padding: 0 5px;
  font-weight: 600;
  font-family: Georgia, "Times New Roman", serif;
}

.heading-group .markdown-tool-btn {
  min-width: 30px;
}



/* Loading indicators */
.loading {
  opacity: 0.6;
  pointer-events: none;
}

/* Focus outline for accessibility */
button:focus, 
a:focus {
  outline: 2px solid var(--accent-color);
  outline-offset: 2px;
}

/* Animation for copied message */
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

/* Tooltip styles */
.tooltip {
  position: absolute;
  background: var(--button-bg);
  border: 1px solid var(--border-color);
  padding: 5px 8px;
  border-radius: 4px;
  font-size: 12px;
  z-index: 1000;
  animation: fadeIn 0.2s ease;
}

/* Styles for GitHub markdown preview light mode */
.markdown-body {
  color-scheme: light;
  --color-prettylights-syntax-comment: #6a737d;
  --color-prettylights-syntax-constant: #005cc5;
  --color-prettylights-syntax-entity: #6f42c1;
  --color-prettylights-syntax-storage-modifier-import: #24292e;
  --color-prettylights-syntax-entity-tag: #22863a;
  --color-prettylights-syntax-keyword: #cf222e;
  --color-prettylights-syntax-string: #032f62;
  --color-prettylights-syntax-variable: #e36209;
  --color-prettylights-syntax-brackethighlighter-unmatched: #b31d28;
  --color-prettylights-syntax-invalid-illegal-text: #fafbfc;
  --color-prettylights-syntax-invalid-illegal-bg: #b31d28;
  --color-prettylights-syntax-carriage-return-text: #fafbfc;
  --color-prettylights-syntax-carriage-return-bg: #d73a49;
  --color-prettylights-syntax-string-regexp: #22863a;
  --color-prettylights-syntax-markup-list: #735c0f;
  --color-prettylights-syntax-markup-heading: #005cc5;
  --color-prettylights-syntax-markup-italic: #24292e;
  --color-prettylights-syntax-markup-bold: #24292e;
  --color-prettylights-syntax-markup-deleted-text: #b31d28;
  --color-prettylights-syntax-markup-deleted-bg: #ffeef0;
  --color-prettylights-syntax-markup-inserted-text: #22863a;
  --color-prettylights-syntax-markup-inserted-bg: #f0fff4;
  --color-prettylights-syntax-markup-changed-text: #e36209;
  --color-prettylights-syntax-markup-changed-bg: #ffebda;
  --color-prettylights-syntax-markup-ignored-text: #f6f8fa;
  --color-prettylights-syntax-markup-ignored-bg: #005cc5;
  --color-prettylights-syntax-meta-diff-range: #6f42c1;
  --color-prettylights-syntax-brackethighlighter-angle: #586069;
  --color-prettylights-syntax-sublimelinter-gutter-mark: #e1e4e8;
  --color-prettylights-syntax-constant-other-reference-link: #032f62;
  --color-fg-default: #24292e;
  --color-fg-muted: #586069;
  --color-fg-subtle: #6a737d;
  --color-canvas-default: #ffffff;
  --color-canvas-subtle: #f6f8fa;
  --color-border-default: #e1e4e8;
  --color-border-muted: #eaecef;
  --color-neutral-muted: rgba(175,184,193,0.2);
  --color-accent-fg: #0366d6;
  --color-accent-emphasis: #0366d6;
  --color-attention-subtle: #fff5b1;
  --color-danger-fg: #d73a49;
}

/* Styles for GitHub markdown preview dark mode */
[data-theme="dark"] .markdown-body {
  color-scheme: dark;
  --color-prettylights-syntax-comment: #8b949e;
  --color-prettylights-syntax-constant: #79c0ff;
  --color-prettylights-syntax-entity: #d2a8ff;
  --color-prettylights-syntax-storage-modifier-import: #c9d1d9;
  --color-prettylights-syntax-entity-tag: #7ee787;
  --color-prettylights-syntax-keyword: #ff7b72;
  --color-prettylights-syntax-string: #a5d6ff;
  --color-prettylights-syntax-variable: #ffa657;
  --color-prettylights-syntax-brackethighlighter-unmatched: #f85149;
  --color-prettylights-syntax-invalid-illegal-text: #f0f6fc;
  --color-prettylights-syntax-invalid-illegal-bg: #8e1519;
  --color-prettylights-syntax-carriage-return-text: #f0f6fc;
  --color-prettylights-syntax-carriage-return-bg: #b62324;
  --color-prettylights-syntax-string-regexp: #7ee787;
  --color-prettylights-syntax-markup-list: #f2cc60;
  --color-prettylights-syntax-markup-heading: #1f6feb;
  --color-prettylights-syntax-markup-italic: #c9d1d9;
  --color-prettylights-syntax-markup-bold: #c9d1d9;
  --color-prettylights-syntax-markup-deleted-text: #ffdcd7;
  --color-prettylights-syntax-markup-deleted-bg: #67060c;
  --color-prettylights-syntax-markup-inserted-text: #aff5b4;
  --color-prettylights-syntax-markup-inserted-bg: #033a16;
  --color-prettylights-syntax-markup-changed-text: #ffdfb6;
  --color-prettylights-syntax-markup-changed-bg: #5a1e02;
  --color-prettylights-syntax-markup-ignored-text: #c9d1d9;
  --color-prettylights-syntax-markup-ignored-bg: #1158c7;
  --color-prettylights-syntax-meta-diff-range: #d2a8ff;
  --color-prettylights-syntax-brackethighlighter-angle: #8b949e;
  --color-prettylights-syntax-sublimelinter-gutter-mark: #484f58;
  --color-prettylights-syntax-constant-other-reference-link: #a5d6ff;
  --color-fg-default: #c9d1d9;
  --color-fg-muted: #8b949e;
  --color-fg-subtle: #484f58;
  --color-canvas-default: #0d1117;
  --color-canvas-subtle: #161b22;
  --color-border-default: #30363d;
  --color-border-muted: #21262d;
  --color-neutral-muted: rgba(110,118,129,0.4);
  --color-accent-fg: #58a6ff;
  --color-accent-emphasis: #1f6feb;
  --color-attention-subtle: rgba(187,128,9,0.15);
  --color-danger-fg: #f85149;
}

/* Override specific styles for dark mode tables and code */
[data-theme="dark"] .markdown-body table tr {
  background-color: var(--table-bg);
}

[data-theme="dark"] .markdown-body table tr:nth-child(2n) {
  background-color: #1c2128; /* Slightly lighter than base dark background */
}

[data-theme="dark"] .markdown-body pre {
  background-color: var(--code-bg);
}

[data-theme="dark"] .markdown-body code {
  background-color: var(--code-bg);
}

/* Syntax Highlighting Mapping to GitHub Variables */
.hljs {
  color: var(--color-fg-default);
}
.hljs-doctag,
.hljs-keyword,
.hljs-meta .hljs-keyword,
.hljs-template-tag,
.hljs-template-variable,
.hljs-type,
.hljs-variable.language_ {
  color: var(--color-prettylights-syntax-keyword);
}
.hljs-title,
.hljs-title.class_,
.hljs-title.class_.inherited__,
.hljs-title.function_ {
  color: var(--color-prettylights-syntax-entity);
}
.hljs-attr,
.hljs-attribute,
.hljs-literal,
.hljs-meta,
.hljs-number,
.hljs-operator,
.hljs-variable,
.hljs-selector-attr,
.hljs-selector-class,
.hljs-selector-id {
  color: var(--color-prettylights-syntax-constant);
}
.hljs-regexp,
.hljs-string,
.hljs-meta .hljs-string {
  color: var(--color-prettylights-syntax-string);
}
.hljs-built_in,
.hljs-symbol {
  color: var(--color-prettylights-syntax-variable);
}
.hljs-comment,
.hljs-code,
.hljs-formula {
  color: var(--color-prettylights-syntax-comment);
}
.hljs-name,
.hljs-quote,
.hljs-selector-tag,
.hljs-selector-pseudo {
  color: var(--color-prettylights-syntax-entity-tag);
}
.hljs-subst {
  color: var(--color-fg-default);
}
.hljs-section {
  color: var(--color-prettylights-syntax-markup-heading);
  font-weight: bold;
}
.hljs-bullet {
  color: var(--color-prettylights-syntax-constant);
}
.hljs-emphasis {
  color: var(--color-fg-default);
  font-style: italic;
}
.hljs-strong {
  color: var(--color-fg-default);
  font-weight: bold;
}
.hljs-addition {
  color: var(--color-prettylights-syntax-markup-inserted-text);
  background-color: var(--color-prettylights-syntax-markup-inserted-bg);
}
.hljs-deletion {
  color: var(--color-prettylights-syntax-markup-deleted-text);
  background-color: var(--color-prettylights-syntax-markup-deleted-bg);
}

.stats-container {
  font-size: 0.8rem;
  color: var(--text-color);
}

.stat-item {
  align-items: center;
}

.stat-item i {
  font-size: 0.9rem;
  opacity: 0.8;
}

#importDropdown,
#exportDropdown,
#languageDropdown {
  font-size: 0.8rem;
}

#importDropdown i,
#exportDropdown i,
#languageDropdown i {
  font-size: 0.9rem;
}

/* Ensure desktop dropdown menu options match the stats-container font size */
[aria-labelledby="importDropdown"] .dropdown-item,
[aria-labelledby="exportDropdown"] .dropdown-item,
[aria-labelledby="languageDropdown"] .dropdown-item {
  font-size: 0.8rem;
}

/* Ensure mobile menu import, export, and language dropdown triggers/options match the mobile stats-container font size */
#mobile-import-button,
#mobile-import-github-button,
#mobile-export-md,
#mobile-export-html,
#mobile-export-pdf,
#mobileLanguageDropdown {
  font-size: 0.9rem !important;
}

[aria-labelledby="mobileLanguageDropdown"] .dropdown-item {
  font-size: 0.9rem;
}

.editor-pane {
  overflow: hidden;
}

/* Mobile Menu Styles */
.mobile-menu {
  display: none;
  position: relative;
  z-index: 1001;
}



/* slide‑in panel */
.mobile-menu-panel {
  position: fixed;
  top: 0;
  right: -300px;
  width: 280px;
  height: 100vh;
  background-color: var(--bg-color);
  box-shadow: -2px 0 10px rgba(0, 0, 0, 0.2);
  transition: right 0.3s ease;
  overflow-y: auto;
  padding: 1rem;
  display: flex;
  flex-direction: column;
  z-index: 1002;
}

.mobile-menu-panel.active {
  right: 0;
}

/* translucent overlay behind panel */
.mobile-menu-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100vh;
  background-color: rgba(0, 0, 0, 0.5);
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: opacity 0.3s ease, visibility 0.3s ease;
  z-index: 1000;
}

.mobile-menu-overlay.active {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
}

/* header inside mobile menu */
.mobile-menu-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
}

.mobile-menu-header h5 {
  margin: 0;
  font-size: 1.25rem;
  color: var(--text-color);
}

/* stats section in mobile menu */
.mobile-stats-container {
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.75rem;
  margin-bottom: 1rem;
}

.mobile-stats-container .stat-item {
  font-size: 0.9rem;
  color: var(--text-color);
  display: flex;
  align-items: center;
}

.mobile-stats-container .stat-item i {
  margin-right: 0.5em;
  opacity: 0.8;
}

/* menu buttons list */
.mobile-menu-items {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  flex-grow: 1;
}

/* each menu item */
.mobile-menu-item {
  background-color: var(--button-bg);
  border: 1px solid var(--border-color);
  color: var(--text-color);
  border-radius: 6px;
  padding: 0.6rem 1rem;
  font-size: 1rem;
  text-align: left;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  transition: background-color 0.2s ease;
  cursor: pointer;
}

.mobile-menu-item:hover {
  background-color: var(--button-hover);
}

.mobile-menu-item:active {
  background-color: var(--button-active);
}

/* close button override */
#close-mobile-menu.tool-button {
  padding: 0.25rem 0.5rem;
  font-size: 1rem;
}

/* Mobile document tabs section */
.mobile-tabs-section {
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.75rem;
}

.mobile-tabs-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.5rem;
}

.mobile-tabs-label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-color);
  opacity: 0.8;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.mobile-new-tab-btn {
  background: none;
  border: 1px solid var(--border-color);
  border-radius: 4px;
  color: var(--text-color);
  padding: 2px 7px;
  font-size: 0.9rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  transition: background-color 0.15s ease;
}

.mobile-new-tab-btn:hover {
  background-color: var(--button-hover);
}

.mobile-tab-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
  max-height: 180px;
  overflow-y: auto;
}

.mobile-tab-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background-color: var(--button-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  padding: 0.45rem 0.75rem;
  font-size: 0.9rem;
  color: var(--text-color);
  cursor: pointer;
  transition: background-color 0.15s ease;
  gap: 0.5rem;
}

.mobile-tab-item:hover {
  background-color: var(--button-hover);
}

.mobile-tab-item.active {
  border-color: var(--accent-color);
  color: var(--accent-color);
  background-color: var(--bg-color);
}

.mobile-tab-title {
  flex: 1;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  min-width: 0;
}

.mobile-tab-item .tab-menu-btn {
  opacity: 0.6;
}

.mobile-tab-item:hover .tab-menu-btn,
.mobile-tab-item.active .tab-menu-btn {
  opacity: 0.8;
}

#mobile-tab-reset-btn {
  margin-left: 0;
  height: auto;
  padding: 0.45rem 0.75rem;
  justify-content: center;
  font-size: 0.9rem;
}

/* ==========================================
   NAVBAR RESPONSIVE BREAKPOINTS
   >= 1080px : full desktop navbar
   <  1080px : mobile hamburger + stacked panes
   ========================================== */

/* Mobile / tablet (< 1080px): switch to hamburger, stack panes */
@media (max-width: 1079px) {
  /* Override Bootstrap d-md-flex / d-md-none so the breakpoint is 1080px */
  .stats-container,
  .toolbar {
    display: none !important;
  }

  /* Expand touch target sizes to meet WCAG mobile guidelines */
  .markdown-tool-btn {
    width: 36px !important;
    height: 36px !important;
    font-size: 16px !important;
  }
  .markdown-format-toolbar {
    height: 44px !important;
  }
  .tab-close-btn {
    width: 28px !important;
    height: 28px !important;
    font-size: 14px !important;
  }
  .tab-menu-btn {
    width: 28px !important;
    height: 28px !important;
    font-size: 14px !important;
  }

  .mobile-menu {
    display: block !important;
  }

  /* Stack editor and preview vertically */
  .content-container {
    flex-direction: column;
  }

  .editor-pane,
  .preview-pane {
    flex: none;
    height: 50%;
    border-right: none;
  }

  .editor-pane {
    border-bottom: 1px solid var(--border-color);
  }

  /* Hide drag-resize divider (touch devices don't use it) */
  .resize-divider {
    display: none;
  }

  /* Single-pane view modes: occupy full height */
  .content-container.view-editor-only .editor-pane,
  .content-container.view-preview-only .preview-pane {
    height: 100%;
  }

  .content-container.view-split .editor-pane,
  .content-container.view-split .preview-pane {
    height: 50%;
  }
}

.github-link {
  color: var(--text-color);
  text-decoration: none;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: transform 0.2s ease, color 0.2s ease;
  margin-right: 2rem;
}

.github-link:hover {
  color: var(--accent-color);
  transform: scale(1.1);
}

.github-link i {
  font-size: 1.25rem;
}

/* ========================================
   HEADER LAYOUT
   ======================================== */
.header-container {
  position: relative;
  min-height: 30px;
}

.app-header h1 {
  font-size: 1.05rem;
  line-height: 1.1;
}

.header-left {
  flex: 1 0 auto;
  justify-content: flex-start;
  white-space: nowrap;
}

.header-right {
  flex: 1 0 auto;
  justify-content: flex-end;
  white-space: nowrap;
}

/* Pane View States */
.content-container.view-editor-only .preview-pane {
  display: none;
}

.content-container.view-editor-only .editor-pane {
  flex: 1;
  border-right: none;
}

.content-container.view-preview-only .editor-pane {
  display: none;
}

.content-container.view-preview-only .preview-pane {
  flex: 1;
}

.content-container.view-split .editor-pane,
.content-container.view-split .preview-pane {
  flex: 1;
}

/* Compact desktop (< 1280px): compact toolbar */
@media (max-width: 1280px) {
  /* Compact toolbar at medium widths */
  .toolbar {
    gap: 4px;
  }
}



/* ========================================
   RESIZE DIVIDER - Story 1.3
   ======================================== */

.resize-divider {
  width: 8px;
  background-color: transparent;
  cursor: col-resize;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  position: relative;
  z-index: 10;
  transition: background-color 0.2s ease;
}

.resize-divider:hover {
  background-color: var(--button-hover);
}

.resize-divider.dragging {
  background-color: var(--accent-color);
}

.resize-divider-handle {
  width: 2px;
  height: 40px;
  background-color: var(--border-color);
  border-radius: 2px;
  transition: background-color 0.2s ease, width 0.2s ease;
}

.resize-divider:hover .resize-divider-handle,
.resize-divider.dragging .resize-divider-handle {
  background-color: var(--accent-color);
  width: 3px;
}

/* Hide divider in single-pane modes */
.content-container.view-editor-only .resize-divider,
.content-container.view-preview-only .resize-divider {
  display: none;
}



/* Prevent text selection during drag */
.resizing {
  user-select: none;
  cursor: col-resize !important;
}

.resizing * {
  cursor: col-resize !important;
}

.resizing #markdown-preview,
.resizing #markdown-editor,
.resizing .line-numbers {
  pointer-events: none !important;
}

/* ========================================
   MOBILE VIEW MODE CONTROLS - Story 1.4
   ======================================== */

.mobile-view-mode-group {
  display: flex;
  gap: 0;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.75rem;
}

.mobile-view-mode-btn {
  flex: 1;
  background-color: var(--button-bg);
  border: 1px solid var(--border-color);
  color: var(--text-color);
  padding: 8px 12px;
  font-size: 14px;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  transition: all 0.2s ease;
}

.mobile-view-mode-btn:first-child {
  border-radius: 6px 0 0 6px;
}

.mobile-view-mode-btn:last-child {
  border-radius: 0 6px 6px 0;
}

.mobile-view-mode-btn:not(:last-child) {
  border-right: none;
}

.mobile-view-mode-btn:hover,
.mobile-view-mode-btn:active {
  background-color: var(--button-hover);
}

.mobile-view-mode-btn.active {
  background-color: var(--button-bg);
  border-color: var(--accent-color);
  color: var(--accent-color);
  border-width: 2px;
  padding: 7px 11px;
}

.mobile-view-mode-btn.active:not(:last-child) {
  border-right: 2px solid var(--accent-color);
}

.mobile-view-mode-btn i {
  font-size: 18px;
}

.mobile-view-mode-btn span {
  font-size: 12px;
}

/* ========================================
   RESPONSIVE VIEW MODE FIXES - Story 1.5
   ======================================== */



/* ========================================
   PDF EXPORT TABLE FIX - Rowspan/Colspan
   ======================================== */

/* Fix for html2canvas not properly rendering rowspan/colspan cells.
   Apply backgrounds to cells instead of rows to prevent row backgrounds
   from painting over rowspan cells during canvas capture. */
.pdf-export table tr {
  background-color: transparent !important;
}

.pdf-export table th,
.pdf-export table td {
  background-color: var(--table-bg, #ffffff);
  position: relative;
}

.pdf-export table tr:nth-child(2n) th,
.pdf-export table tr:nth-child(2n) td {
  background-color: var(--bg-color, #f6f8fa);
}

/* Ensure rowspan cells render correctly */
.pdf-export table th[rowspan],
.pdf-export table td[rowspan] {
  vertical-align: middle;
  background-color: var(--table-bg, #ffffff) !important;
}

/* Ensure colspan cells render correctly */
.pdf-export table th[colspan],
.pdf-export table td[colspan] {
  text-align: center;
}

/* Dark mode PDF export table fix */
[data-theme="dark"] .pdf-export table th,
[data-theme="dark"] .pdf-export table td {
  background-color: var(--table-bg, #161b22);
}

[data-theme="dark"] .pdf-export table tr:nth-child(2n) th,
[data-theme="dark"] .pdf-export table tr:nth-child(2n) td {
  background-color: #1c2128;
}

[data-theme="dark"] .pdf-export table th[rowspan],
[data-theme="dark"] .pdf-export table td[rowspan] {
  background-color: var(--table-bg, #161b22) !important;
}

/* ========================================
   MERMAID DIAGRAM TOOLBAR
   ======================================== */

.mermaid-container {
  position: relative;
}

.mermaid-toolbar {
  position: absolute;
  top: 8px;
  right: 8px;
  display: flex;
  gap: 4px;
  opacity: 0;
  transition: opacity 0.2s ease;
  z-index: 10;
}

.mermaid-container:hover .mermaid-toolbar {
  opacity: 1;
}

.mermaid-toolbar-btn {
  background-color: var(--button-bg);
  border: 1px solid var(--border-color);
  color: var(--text-color);
  border-radius: 4px;
  padding: 4px 7px;
  font-size: 13px;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 3px;
  transition: background-color 0.2s ease, color 0.2s ease;
  white-space: nowrap;
}

.mermaid-toolbar-btn:hover {
  background-color: var(--button-hover);
  color: var(--accent-color);
}

.mermaid-toolbar-btn:active {
  background-color: var(--button-active);
}

.mermaid-toolbar-btn i {
  font-size: 14px;
}

/* ========================================
   MERMAID ZOOM MODAL
   ======================================== */

#mermaid-zoom-modal {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 2000;
  background-color: rgba(0, 0, 0, 0.75);
  align-items: center;
  justify-content: center;
}

#mermaid-zoom-modal.active {
  display: flex;
}

.mermaid-modal-content {
  background-color: var(--bg-color);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 16px;
  width: 85vw;
  height: 85vh;
  max-width: 85vw;
  max-height: 85vh;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

@media (max-width: 576px) {
  .mermaid-modal-content {
    width: 95vw;
    height: 90vh;
    max-width: 95vw;
    max-height: 90vh;
    padding: 10px;
  }
}

.mermaid-modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.mermaid-modal-header span {
  font-weight: 600;
  font-size: 15px;
  color: var(--text-color);
}

.mermaid-modal-close {
  background: none;
  border: none;
  color: var(--text-color);
  font-size: 1.2rem;
  cursor: pointer;
  padding: 2px 6px;
  border-radius: 4px;
  display: flex;
  align-items: center;
  transition: background-color 0.2s ease;
}

.mermaid-modal-close:hover {
  background-color: var(--button-hover);
}

.mermaid-modal-diagram {
  overflow: auto;
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 200px;
  cursor: grab;
}

.mermaid-modal-diagram.dragging {
  cursor: grabbing;
}

.mermaid-modal-diagram svg {
  transform-origin: center;
  transition: transform 0.1s ease;
  max-width: none;
}

.mermaid-modal-controls {
  display: flex;
  justify-content: center;
  gap: 8px;
  flex-wrap: wrap;
}

.mermaid-modal-controls .mermaid-toolbar-btn {
  opacity: 1;
}

/* ========================================
   DOCUMENT TABS & SESSION MANAGEMENT
   ======================================== */

.tab-bar {
  display: flex;
  align-items: center;
  background-color: var(--header-bg);
  border-bottom: 1px solid var(--border-color);
  height: 32px;
  overflow: visible;  /* ← was: overflow: hidden */
  flex-shrink: 0;
  padding: 0 4px;
  gap: 0;
  user-select: none;
  position: relative;
  z-index: 10;
}

.tab-list {
  display: flex;
  align-items: flex-end;
  overflow-x: auto;
  overflow-y: visible;  /* ← was: overflow-y: hidden */
  flex: 1;
  height: 100%;
  scrollbar-width: none;
  -ms-overflow-style: none;
}

.tab-list::-webkit-scrollbar {
  display: none;
}

.tab-item {
  display: flex;
  align-items: center;
  gap: 6px;
  height: 32px;
  padding: 0 8px 0 10px;
  min-width: 100px;
  max-width: 180px;
  background-color: var(--button-bg);
  border: 1px solid var(--border-color);
  border-bottom: 1px solid transparent;
  border-radius: 6px 6px 0 0;
  cursor: pointer;
  font-size: 13px;
  color: var(--text-color);
  white-space: nowrap;
  /* overflow: hidden; <-- REMOVE THIS */
  position: relative;
  transition: background-color 0.15s ease, color 0.15s ease;
  flex-shrink: 0;
  margin-right: 2px;
  opacity: 0.7;
}

.tab-item:hover {
  background-color: var(--button-hover);
  opacity: 0.9;
}

.tab-item.active {
  background-color: var(--bg-color);
  border-color: var(--border-color);
  color: var(--accent-color);
  border-bottom: 1px solid var(--bg-color);
  opacity: 1;
  z-index: 2;
}

.tab-item.unsaved::after {
  content: '';
  display: inline-block;
  width: 6px;
  height: 6px;
  background-color: var(--accent-color);
  border-radius: 50%;
  flex-shrink: 0;
  margin-left: 2px;
}

.tab-title {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  flex: 1;
  min-width: 0;
}

.tab-close-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 16px;
  height: 16px;
  border-radius: 3px;
  background: none;
  border: none;
  color: var(--text-color);
  cursor: pointer;
  padding: 0;
  font-size: 11px;
  opacity: 0;
  flex-shrink: 0;
  transition: background-color 0.15s ease, opacity 0.15s ease;
}

.tab-item:hover .tab-close-btn,
.tab-item.active .tab-close-btn {
  opacity: 0.6;
}

.tab-close-btn:hover {
  background-color: var(--button-active);
  opacity: 1 !important;
  color: var(--color-danger-fg, #d73a49);
}

.tab-new-btn {
  display: flex;
  align-items: center;
  gap: 4px;
  height: 24px;
  padding: 0 8px;
  border-radius: 5px;
  background: none;
  border: 1px solid var(--border-color);
  color: var(--text-color);
  cursor: pointer;
  font-size: 12px;
  flex-shrink: 0;
  margin-left: 6px;
  align-self: center;
  transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}

.tab-new-btn:hover {
  background-color: rgba(46, 160, 67, 0.1);
  border-color: var(--accent-color, #2ea043);
  color: var(--accent-color, #2ea043);
}

.tab-new-btn:active {
  background-color: rgba(46, 160, 67, 0.2);
}

/* Drag-and-drop visual feedback */
.tab-item.dragging {
  opacity: 0.4;
}

.tab-item.drag-over {
  border-left: 2px solid var(--accent-color);
}

/* Tab enter animation */
@keyframes tabSlideIn {
  from { opacity: 0; transform: translateY(4px); }
  to   { opacity: 0.7; transform: translateY(0); }
}

.tab-item {
  animation: tabSlideIn 0.12s ease forwards;
}

.tab-item.active {
  animation: none;
}

/* Hide tab bar on very small screens — single-file use */
@media (max-width: 480px) {
  .tab-bar {
    display: none;
  }
}

/* ========================================
   TAB OVERFLOW — Scroll Buttons & Fade Indicators
   ======================================== */

.tab-scroll-btn {
  display: none;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  border-radius: 4px;
  background: none;
  border: 1px solid transparent;
  color: var(--text-color);
  cursor: pointer;
  font-size: 14px;
  flex-shrink: 0;
  padding: 0;
  transition: background-color 0.15s ease, border-color 0.15s ease, opacity 0.15s ease;
  z-index: 2;
  opacity: 0.6;
}

.tab-scroll-btn:hover {
  background-color: var(--button-hover);
  border-color: var(--border-color);
  opacity: 1;
}

.tab-scroll-btn:active {
  background-color: var(--button-active);
}

/* Show scroll buttons only when overflow exists */
.tab-bar.has-overflow-left .tab-scroll-left,
.tab-bar.has-overflow-right .tab-scroll-right {
  display: flex;
}

/* Overflow fade indicators — subtle gradient at clipped edges */
.tab-list::before,
.tab-list::after {
  content: '';
  position: sticky;
  top: 0;
  bottom: 0;
  width: 0;
  flex-shrink: 0;
  pointer-events: none;
  z-index: 3;
  transition: box-shadow 0.2s ease;
}

.tab-list::before {
  left: 0;
}

.tab-list::after {
  right: 0;
}

.tab-bar.has-overflow-left .tab-list::before {
  box-shadow: 8px 0 12px -4px rgba(0, 0, 0, 0.12);
}

.tab-bar.has-overflow-right .tab-list::after {
  box-shadow: -8px 0 12px -4px rgba(0, 0, 0, 0.12);
}

[data-theme="dark"] .tab-bar.has-overflow-left .tab-list::before {
  box-shadow: 8px 0 12px -4px rgba(0, 0, 0, 0.35);
}

[data-theme="dark"] .tab-bar.has-overflow-right .tab-list::after {
  box-shadow: -8px 0 12px -4px rgba(0, 0, 0, 0.35);
}

/* ========================================
   THREE-DOT TAB MENU
   ======================================== */

.tab-menu-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 22px;
  height: 22px;
  border-radius: 3px;
  background: none;
  border: none;
  color: var(--text-color);
  cursor: pointer;
  padding: 0;
  font-size: 14px;
  font-weight: bold;
  letter-spacing: 1px;
  opacity: 0.65;
  flex-shrink: 0;
  transition: background-color 0.15s ease, opacity 0.15s ease;
  position: relative;
}

/* Touch Hitbox Expansion for Tab Menu Button */
.tab-menu-btn::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 48px;
  height: 48px;
}

/* Touch-optimized styling for coarser pointers (e.g., smartphones & tablets) */
@media (pointer: coarse) {
  .tab-bar {
    height: 40px !important;
  }
  .tab-item {
    height: 40px !important;
    font-size: 14px !important;
    padding: 0 10px 0 12px !important;
    gap: 8px !important;
  }
  .tab-new-btn,
  .tab-reset-btn {
    height: 32px !important;
    font-size: 14px !important;
    padding: 0 12px !important;
  }
  .tab-scroll-btn {
    width: 32px !important;
    height: 32px !important;
    font-size: 18px !important;
  }
  .tab-menu-btn {
    width: 30px !important;
    height: 30px !important;
    font-size: 18px !important;
  }
  .tab-close-btn {
    width: 20px !important;
    height: 20px !important;
    font-size: 13px !important;
    opacity: 0.8 !important;
  }
}

.tab-item:hover .tab-menu-btn,
.tab-item.active .tab-menu-btn {
  opacity: 0.65;
}

.tab-menu-btn:hover {
  background-color: var(--button-active);
  opacity: 1 !important;
}

.tab-menu-dropdown {
  display: none;
  position: fixed;
  min-width: 130px;
  background-color: var(--header-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  box-shadow: 0 4px 12px rgba(0,0,0,0.15);
  z-index: 99999;
  overflow: hidden;
  flex-direction: column;
}

.tab-menu-dropdown.open {
  display: flex;
}

.tab-menu-item {
  display: flex;
  align-items: center;
  gap: 7px;
  padding: 7px 12px;
  background: none;
  border: none;
  color: var(--text-color);
  font-size: 12px;
  cursor: pointer;
  text-align: left;
  transition: background-color 0.12s ease;
  white-space: nowrap;
}

.tab-menu-item:hover {
  background-color: var(--button-hover);
}

.tab-menu-item-danger {
  color: var(--color-danger-fg, #d73a49);
}

.tab-menu-item-danger:hover {
  background-color: rgba(215, 58, 73, 0.1);
}

/* ========================================
   RESET BUTTON
   ======================================== */

.tab-reset-btn {
  display: flex;
  align-items: center;
  gap: 4px;
  height: 24px;
  padding: 0 8px;
  border-radius: 5px;
  background: none;
  border: 1px solid var(--border-color);
  color: var(--text-color);
  cursor: pointer;
  font-size: 12px;
  flex-shrink: 0;
  margin-left: 6px;
  transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}

.tab-reset-btn:hover {
  background-color: rgba(215, 58, 73, 0.1);
  border-color: var(--color-danger-fg, #d73a49);
  color: var(--color-danger-fg, #d73a49);
}

/* ========================================
   RESET & RENAME CONFIRMATION MODALS
   ======================================== */

.reset-modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.45);
  z-index: 2000;
  display: flex;
  align-items: center;
  justify-content: center;
}

.reset-modal-overlay.modal-overlay {
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.2s ease, visibility 0.2s ease;
}

.reset-modal-overlay.modal-overlay.is-visible {
  opacity: 1;
  visibility: visible;
}

.reset-modal-box {
  background: var(--header-bg);
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 24px 28px;
  min-width: 280px;
  max-width: 360px;
  box-shadow: 0 8px 32px rgba(0,0,0,0.25);
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.modal-box {
  max-height: min(85vh, 760px);
  opacity: 0;
  transform: translateY(8px);
  transition: transform 0.2s ease, opacity 0.2s ease;
}

.reset-modal-overlay.modal-overlay.is-visible .modal-box {
  opacity: 1;
  transform: translateY(0);
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.modal-header .reset-modal-message {
  text-align: left;
  flex: 1;
}

.modal-close-btn {
  border: 1px solid var(--border-color);
  background: var(--button-bg);
  color: var(--text-color);
  border-radius: 6px;
  width: 28px;
  height: 28px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: background-color 0.15s ease;
}

.modal-close-btn:hover {
  background-color: var(--button-hover);
}

.modal-body {
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-height: min(60vh, 520px);
  overflow: auto;
  padding-right: 4px;
}

.modal-section {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.modal-section-title {
  margin: 0;
  font-size: 0.95rem;
  font-weight: 600;
}

.modal-list {
  margin: 0;
  padding-left: 1.1rem;
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: 0.85rem;
}

.modal-list a {
  color: var(--accent-color);
  text-decoration: none;
}

.modal-list a:hover {
  text-decoration: underline;
}

.modal-subtext {
  margin: 0;
  font-size: 12px;
  color: var(--text-secondary, #57606a);
  line-height: 1.4;
}

.find-replace-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.find-match-count {
  font-size: 12px;
  color: var(--text-secondary, #57606a);
}

.find-replace-nav {
  display: inline-flex;
  gap: 6px;
}

.find-nav-btn {
  width: 28px;
  height: 28px;
  padding: 0;
}

.about-header {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.about-logo {
  width: 64px;
  height: 64px;
  border-radius: 12px;
  border: 1px solid var(--border-color);
  object-fit: cover;
}

.about-details {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.about-title {
  margin: 0;
  font-size: 1.05rem;
  font-weight: 600;
}

.about-description {
  margin: 0;
  font-size: 0.85rem;
  color: var(--text-secondary, #57606a);
}

.about-meta {
  margin: 0;
  font-size: 0.78rem;
  color: var(--text-secondary, #57606a);
}

.modal-body kbd {
  padding: 2px 6px;
  border-radius: 4px;
  background-color: var(--button-bg);
  border: 1px solid var(--border-color);
  font-size: 0.75rem;
  font-family: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
}

.reset-modal-box--wide {
  width: min(92vw, 640px);
  max-width: 640px;
}

.reset-modal-message {
  margin: 0;
  font-size: 14px;
  color: var(--text-color);
  font-weight: 500;
  text-align: center;
}

.reset-modal-actions {
  display: flex;
  gap: 10px;
  justify-content: flex-end;
}

.reset-modal-btn {
  padding: 6px 16px;
  border-radius: 6px;
  border: 1px solid var(--border-color);
  background: var(--button-bg);
  color: var(--text-color);
  font-size: 13px;
  cursor: pointer;
  transition: background-color 0.15s ease;
}

.reset-modal-btn:hover {
  background-color: var(--button-hover);
}

.reset-modal-confirm {
  background-color: var(--color-danger-fg, #d73a49);
  border-color: var(--color-danger-fg, #d73a49);
  color: #fff;
}

.reset-modal-confirm:hover {
  background-color: #b02a37;
  border-color: #b02a37;
}

/* ========================================
   PDF EXPORT PROGRESS MODAL
   ======================================== */

.pdf-progress-overlay {
  position: fixed;
  inset: 0;
  z-index: 2600;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0, 0, 0, 0.45);
  padding: 20px;
}

.pdf-progress-modal {
  width: min(92vw, 420px);
  background: var(--header-bg);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  box-shadow: 0 16px 48px rgba(0, 0, 0, 0.28);
  color: var(--text-color);
  display: flex;
  flex-direction: column;
  gap: 16px;
  padding: 20px;
}

.pdf-progress-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.pdf-progress-title {
  margin: 0;
  font-size: 15px;
  font-weight: 600;
}

.pdf-progress-percent {
  font-size: 28px;
  font-weight: 600;
  line-height: 1;
}

.pdf-progress-track {
  width: 100%;
  height: 10px;
  background: var(--button-bg);
  border: 1px solid var(--border-color);
  border-radius: 999px;
  overflow: hidden;
}

.pdf-progress-fill {
  width: 0%;
  height: 100%;
  background: var(--accent-color);
  border-radius: inherit;
  transition: width 0.18s ease;
}

.pdf-progress-details {
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: 12px;
  color: var(--text-secondary);
}

.pdf-progress-detail {
  display: flex;
  justify-content: space-between;
  gap: 12px;
}

.pdf-progress-detail strong {
  color: var(--text-color);
  font-weight: 600;
}

.pdf-progress-actions {
  display: flex;
  justify-content: flex-end;
}

.tool-button.pdf-export-loading,
.mobile-menu-item.pdf-export-loading {
  pointer-events: none;
}
/* ========================================
   RESET MODAL FORM FIELDS
   ======================================== */

.reset-modal-field {
  display: flex;
  flex-direction: column;
  gap: 6px;
  text-align: left;
}

.reset-modal-field-group {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.reset-modal-label {
  font-size: 12px;
  color: var(--text-secondary, #57606a);
  font-weight: 600;
}

.reset-modal-toggle-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.reset-modal-option {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--text-color);
}

.reset-modal-option input {
  margin: 0;
}

/* ========================================
   RENAME MODAL INPUT
   ======================================== */

.rename-modal-input {
  width: 100%;
  padding: 7px 10px;
  border-radius: 6px;
  border: 1px solid var(--border-color);
  background: var(--bg-color);
  color: var(--text-color);
  font-size: 13px;
  outline: none;
  box-sizing: border-box;
}

.rename-modal-input:focus {
  border-color: var(--accent-color);
}

/* ========================================
   TOOLBAR POPUP PANELS
   ======================================== */

.reset-modal-box--xl {
  width: min(94vw, 980px);
  max-width: 980px;
}

.modal-empty {
  margin: 0;
  font-size: 12px;
  color: var(--text-secondary, #57606a);
  text-align: center;
}

.emoji-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 12px;
  max-height: min(52vh, 440px);
  overflow: auto;
  padding: 4px;
}

.symbol-grid {
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-height: min(52vh, 440px);
  overflow: auto;
  padding: 4px 2px;
}

.symbol-section-title {
  margin: 0;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-secondary, #57606a);
}

.symbol-section-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
  gap: 12px;
}

.alert-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 12px;
  max-height: min(45vh, 360px);
  overflow: auto;
  padding: 2px;
}

.emoji-item,
.symbol-item,
.alert-option {
  display: flex;
  flex-direction: column;
  gap: 8px;
  align-items: center;
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 10px;
  background: var(--bg-color);
  color: var(--text-color);
  cursor: pointer;
  transition: border-color 0.2s ease, box-shadow 0.2s ease, background-color 0.2s ease;
}

.emoji-item:focus-visible,
.symbol-item:focus-visible,
.alert-option:focus-visible {
  outline: 2px solid var(--accent-color);
  outline-offset: 2px;
}

.emoji-item.is-selected,
.symbol-item.is-selected,
.alert-option.is-selected {
  border-color: var(--accent-color);
  box-shadow: 0 0 0 2px rgba(88, 166, 255, 0.2);
  background-color: rgba(88, 166, 255, 0.08);
}

.emoji-preview {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.emoji-preview img {
  width: 32px;
  height: 32px;
}

.emoji-shortcode {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  color: var(--text-secondary, #57606a);
  text-align: center;
}

.emoji-copy-btn,
.symbol-copy-btn {
  border: none;
  background: transparent;
  color: var(--text-secondary, #57606a);
  cursor: pointer;
  padding: 2px;
  border-radius: 4px;
}

.emoji-copy-btn:hover,
.symbol-copy-btn:hover {
  color: var(--text-color);
  background: var(--button-hover);
}

.emoji-copy-btn.is-copied,
.symbol-copy-btn.is-copied {
  color: var(--accent-color);
}

.symbol-preview {
  font-size: 28px;
  line-height: 1;
}

.symbol-code {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 12px;
  color: var(--text-secondary, #57606a);
}

.alert-option {
  align-items: stretch;
  text-align: left;
  padding: 12px;
}

.alert-preview {
  margin: 0;
}

.alert-preview .markdown-alert {
  padding: 0.5rem 0.9rem;
  border-left: 0.25em solid;
  border-radius: 0.375rem;
}

.alert-preview .markdown-alert-title {
  margin: 0 0 6px;
  font-weight: 600;
  line-height: 1.25;
  display: flex;
  align-items: center;
  gap: 8px;
}

.alert-preview .markdown-alert-icon {
  display: inline-flex;
  width: 16px;
  height: 16px;
}

.alert-preview .markdown-alert-icon svg {
  width: 16px;
  height: 16px;
  fill: currentColor;
}

.alert-preview .markdown-alert > *:not(.markdown-alert-title) {
  color: var(--text-color);
}

.alert-preview .markdown-alert-note {
  color: #0969da;
  border-left-color: #0969da;
  background-color: #ddf4ff;
}

.alert-preview .markdown-alert-tip {
  color: #1a7f37;
  border-left-color: #1a7f37;
  background-color: #dafbe1;
}

.alert-preview .markdown-alert-important {
  color: #8250df;
  border-left-color: #8250df;
  background-color: #fbefff;
}

.alert-preview .markdown-alert-warning {
  color: #9a6700;
  border-left-color: #9a6700;
  background-color: #fff8c5;
}

.alert-preview .markdown-alert-caution {
  color: #cf222e;
  border-left-color: #cf222e;
  background-color: #ffebe9;
}

[data-theme="dark"] .alert-preview .markdown-alert-note {
  color: #4493f8;
  border-left-color: #4493f8;
  background-color: rgba(31, 111, 235, 0.15);
}

[data-theme="dark"] .alert-preview .markdown-alert-tip {
  color: #3fb950;
  border-left-color: #3fb950;
  background-color: rgba(35, 134, 54, 0.15);
}

[data-theme="dark"] .alert-preview .markdown-alert-important {
  color: #ab7df8;
  border-left-color: #ab7df8;
  background-color: rgba(137, 87, 229, 0.15);
}

[data-theme="dark"] .alert-preview .markdown-alert-warning {
  color: #d29922;
  border-left-color: #d29922;
  background-color: rgba(210, 153, 34, 0.18);
}

[data-theme="dark"] .alert-preview .markdown-alert-caution {
  color: #f85149;
  border-left-color: #f85149;
  background-color: rgba(248, 81, 73, 0.18);
}

.github-import-error {
  margin: 0;
  font-size: 12px;
  color: var(--color-danger-fg, #d73a49);
  text-align: left;
  line-height: 1.5;
}

.github-import-error.is-info {
  color: var(--text-secondary, #57606a);
}

#github-import-modal .reset-modal-box {
  width: 60vw;
  max-width: 60vw;
  min-width: 340px;
  padding: 30px 34px;
  gap: 16px;
  box-shadow: 0 20px 48px rgba(0, 0, 0, 0.22);
}

#github-import-modal .reset-modal-message {
  font-size: 18px;
  line-height: 1.35;
  text-align: left;
}

#github-import-url,
#github-import-file-select {
  min-height: 46px;
  padding: 10px 12px;
  font-size: 15px;
}

#github-import-file-select {
  min-height: 180px;
}

.github-import-tree {
  max-height: 420px;
  overflow: auto;
  border: 1px solid var(--border-color);
  border-radius: 10px;
  padding: 12px;
  background: var(--bg-color);
}

.github-import-selection-toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 12px;
  border: 1px solid var(--border-color);
  border-radius: 8px;
  background: var(--button-bg);
}

.github-import-selected-count {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-color);
}

.github-import-tree ul {
  list-style: none;
  margin: 0;
  padding-left: 18px;
}

.github-import-tree > ul {
  padding-left: 4px;
}

.github-import-tree li {
  margin: 2px 0;
}

.github-tree-folder-label {
  display: inline-block;
  font-size: 14px;
  color: var(--text-secondary, #57606a);
  margin-bottom: 4px;
}

.github-tree-file-btn {
  border: 0;
  background: transparent;
  color: var(--text-color);
  cursor: pointer;
  padding: 6px 8px;
  border-radius: 6px;
  text-align: left;
  width: 100%;
  font-size: 14px;
}

.github-tree-file-btn:hover,
.github-tree-file-btn:focus-visible {
  background: var(--button-hover);
  outline: none;
}

.github-tree-file-btn.is-selected {
  background: rgba(56, 139, 253, 0.14);
  color: var(--accent-color);
}

#github-import-modal .reset-modal-actions {
  gap: 12px;
}

#github-import-modal .reset-modal-btn {
  min-height: 42px;
  padding: 9px 18px;
  font-size: 14px;
}

@media (max-width: 576px) {
  #github-import-modal .reset-modal-box {
    width: 95vw;
    max-width: 95vw;
    min-width: 0;
    padding: 20px;
    gap: 14px;
  }

  .github-import-selection-toolbar {
    flex-direction: column;
    align-items: stretch;
  }

  #github-import-modal .reset-modal-message {
    font-size: 16px;
  }

  #github-import-modal .reset-modal-actions {
    flex-direction: column-reverse;
  }

  #github-import-modal .reset-modal-btn {
    width: 100%;
  }
}

.frontmatter-table {
  border-collapse: collapse;
  margin-bottom: 1.5em;
  font-size: 0.9em;
  width: auto;
  max-width: 100%;
}

.frontmatter-table th,
.frontmatter-table td {
  border: 1px solid var(--border-color);
  padding: 6px 13px;
  vertical-align: top;
  color: var(--text-color);
}

.frontmatter-table tr:nth-child(odd) th,
.frontmatter-table tr:nth-child(odd) td {
  background-color: var(--table-bg);
}

.frontmatter-table tr:nth-child(even) th,
.frontmatter-table tr:nth-child(even) td {
  background-color: var(--editor-bg);
}

.frontmatter-table th {
  font-weight: 600;
  text-align: right;
  white-space: nowrap;
  vertical-align: middle;
}

.frontmatter-table td {
  text-align: left;
}

.fm-complex {
  margin: 0;
  padding: 4px 6px;
  font-size: 0.8em;
  font-family: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, monospace;
  white-space: pre-wrap;
  word-break: break-word;
  background: transparent;
  border: none;
  color: var(--text-color);
}

.fm-tag {
  display: inline-block;
  padding: 2px 8px;
  margin: 2px 3px 2px 0;
  border: 1px solid var(--border-color);
  border-radius: 2em;
  font-size: 0.8em;
  font-weight: 500;
  color: var(--accent-color);
  background-color: var(--button-bg);
  white-space: nowrap;
}

/* ========================================
   RTL SUPPORT
   ======================================== */

[dir="rtl"] body {
  direction: rtl;
}

[dir="rtl"] .editor-pane {
  padding-left: 0px;
  padding-right: 20px;
  border-right: none;
  border-left: 1px solid var(--border-color);
}

[dir="rtl"] #markdown-editor,
[dir="rtl"] .markdown-body {
  direction: rtl;
  text-align: right;
}

[dir="rtl"] .markdown-body pre,
[dir="rtl"] .markdown-body code,
[dir="rtl"] .fm-complex {
  direction: ltr;
  text-align: left;
}

[dir="rtl"] .line-numbers {
  left: auto;
  right: 20px;
  padding: 10px 0 10px 8px;
  text-align: left;
  border-right: none;
  border-left: 1px solid var(--border-color);
}

[dir="rtl"] #markdown-editor {
  padding-left: 10px;
  padding-right: calc(10px + var(--line-number-gutter));
}

[dir="rtl"] .editor-highlight-layer {
  inset: 20px calc(20px + var(--line-number-gutter)) 20px 0;
}

[dir="rtl"] .mobile-menu-item,
[dir="rtl"] .tab-menu-item,
[dir="rtl"] .modal-header .reset-modal-message,
[dir="rtl"] .reset-modal-field,
[dir="rtl"] .alert-option,
[dir="rtl"] .github-import-error,
[dir="rtl"] #github-import-modal .reset-modal-message,
[dir="rtl"] .github-tree-file-btn,
[dir="rtl"] .frontmatter-table td {
  text-align: right;
}

[dir="rtl"] .github-import-tree ul {
  padding-left: 0;
  padding-right: 18px;
}

[dir="rtl"] .github-import-tree > ul {
  padding-right: 4px;
}

[dir="rtl"] .markdown-body .markdown-alert,
[dir="rtl"] .alert-preview .markdown-alert {
  border-left: 0;
  border-right: 0.25em solid currentColor;
}

/* ============================================
   SHARE MODAL
   ============================================ */

.share-modal-description {
  font-size: 13px;
  color: var(--text-secondary, #57606a);
  margin: 0;
}

.share-mode-cards {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.share-mode-card {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  border-radius: 8px;
  border: 1px solid var(--border-color);
  background: var(--bg-color);
  cursor: pointer;
  transition: border-color 0.15s ease, background-color 0.15s ease;
  user-select: none;
}

.share-mode-card:hover {
  border-color: var(--accent-color);
  background: var(--button-hover);
}

.share-mode-card.is-selected {
  border-color: var(--accent-color);
  background: color-mix(in srgb, var(--accent-color) 8%, transparent);
}

.share-mode-card input[type="radio"] {
  display: none;
}

.share-card-icon {
  font-size: 18px;
  width: 28px;
  text-align: center;
  color: var(--text-secondary, #57606a);
  flex-shrink: 0;
}

.share-mode-card.is-selected .share-card-icon {
  color: var(--accent-color);
}

.share-card-body {
  display: flex;
  flex-direction: column;
  gap: 2px;
  flex: 1;
  min-width: 0;
}

.share-card-title {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-color);
}

.share-card-desc {
  font-size: 12px;
  color: var(--text-secondary, #57606a);
}

.share-card-check {
  width: 18px;
  text-align: center;
  color: var(--accent-color);
  opacity: 0;
  transition: opacity 0.15s ease;
  flex-shrink: 0;
}

.share-mode-card.is-selected .share-card-check {
  opacity: 1;
}

.share-url-row {
  display: flex;
  gap: 8px;
  align-items: center;
}

.share-url-input {
  flex: 1;
  font-size: 12px;
  font-family: var(--font-mono, monospace);
  color: var(--text-secondary, #57606a);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.share-copy-btn {
  flex-shrink: 0;
  padding: 6px 10px;
}

.share-copy-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.share-modal-notice {
  font-size: 11px;
  color: var(--text-secondary, #57606a);
  margin: 0;
  display: flex;
  align-items: center;
  gap: 5px;
}

/* ==========================================================================
   Multilingual & CJK Optimization styles added by Aegis SEO agency
   ========================================================================== */
.lang-select-item {
  display: flex !important;
  align-items: center;
  gap: 8px;
  cursor: pointer;
  transition: background-color 0.2s ease, padding-left 0.2s ease;
}

.lang-select-item:hover {
  padding-left: 12px;
}

.lang-select-item.active {
  background-color: var(--accent-color) !important;
  color: #ffffff !important;
  font-weight: 600;
}

/* Adjust CJK text layout for maximum readability inside the preview pane */
html[lang="zh"] .markdown-body,
html[lang="ja"] .markdown-body,
html[lang="ko"] .markdown-body {
  line-height: 1.75 !important;
  letter-spacing: 0.03em;
  word-break: keep-all;
  overflow-wrap: break-word;
  text-align: justify;
}

/* Specific heading spacing improvements for CJK characters */
html[lang="zh"] .markdown-body h1, html[lang="zh"] .markdown-body h2, html[lang="zh"] .markdown-body h3,
html[lang="ja"] .markdown-body h1, html[lang="ja"] .markdown-body h2, html[lang="ja"] .markdown-body h3,
html[lang="ko"] .markdown-body h1, html[lang="ko"] .markdown-body h2, html[lang="ko"] .markdown-body h3 {
  font-weight: 700;
  letter-spacing: 0.02em;
  margin-top: 1.4em;
  margin-bottom: 0.6em;
}

/* Smooth fade and scale transition for dropdown active states */
.dropdown-menu {
  opacity: 0;
  transform: translateY(8px) scale(0.98);
  display: block;
  visibility: hidden;
  transition: opacity 0.2s cubic-bezier(0.16, 1, 0.3, 1), transform 0.2s cubic-bezier(0.16, 1, 0.3, 1), visibility 0.2s;
}

.dropdown-menu.show {
  opacity: 1;
  transform: translateY(0) scale(1);
  visibility: visible;
}

/* ========================================
   FIND & REPLACE FLOATING PANEL DESIGN
   ======================================== */

.find-replace-panel {
  position: fixed;
  top: 100px;
  right: 20px;
  width: 340px;
  background-color: var(--fr-bg);
  border: 1px solid var(--fr-border);
  border-radius: 12px;
  box-shadow: var(--fr-shadow);
  z-index: 1050;
  display: flex;
  flex-direction: column;
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  transition: opacity 0.2s ease, transform 0.2s ease;
  user-select: none;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
}

.find-replace-panel.docked {
  position: relative;
  top: 0 !important;
  right: 0 !important;
  height: 100%;
  border-radius: 0;
  border-top: none;
  border-bottom: none;
  border-right: none;
  border-left: 1px solid var(--fr-border);
  box-shadow: none;
  backdrop-filter: none;
  z-index: 10;
  flex-shrink: 0;
}

.find-replace-panel.docked #find-replace-reset,
.find-replace-panel.docked #find-replace-reset-footer {
  display: none !important;
}

.find-replace-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 12px;
  border-bottom: 1px solid var(--fr-border);
  cursor: move;
  background-color: var(--header-bg);
  border-top-left-radius: 11px;
  border-top-right-radius: 11px;
}

.find-replace-panel.docked .find-replace-header {
  cursor: default;
  border-top-left-radius: 0;
  border-top-right-radius: 0;
}

.find-replace-title {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-color);
}

.find-replace-header-actions {
  display: flex;
  gap: 4px;
}

.panel-icon-btn {
  background: none;
  border: none;
  color: var(--text-color);
  font-size: 12px;
  cursor: pointer;
  padding: 2px 6px;
  border-radius: 4px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background-color 0.15s ease;
}

.panel-icon-btn:hover {
  background-color: var(--button-hover);
}

.find-replace-body {
  padding: 12px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.find-replace-field-row {
  display: flex;
  flex-direction: column;
  position: relative;
}

.find-input-container, .replace-input-container {
  display: flex;
  align-items: center;
  border: 1px solid var(--fr-border);
  border-radius: 6px;
  background-color: var(--bg-color);
  padding: 2px 4px;
  width: 100%;
}

.find-input-container:focus-within, .replace-input-container:focus-within {
  border-color: var(--accent-color);
  box-shadow: 0 0 0 3px rgba(9, 105, 218, 0.15);
}

.find-input-field {
  flex: 1;
  border: none;
  background: transparent;
  color: var(--text-color);
  font-size: 13px;
  padding: 4px 6px;
  outline: none;
  width: 50%;
}

.find-options-group {
  display: flex;
  gap: 2px;
}

.find-option-btn {
  background: none;
  border: none;
  color: var(--text-secondary);
  font-size: 11px;
  font-weight: 600;
  cursor: pointer;
  padding: 2px 5px;
  border-radius: 4px;
  transition: background-color 0.12s ease, color 0.12s ease;
  min-width: 22px;
  height: 22px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}

.find-option-btn:hover {
  background-color: var(--button-hover);
  color: var(--text-color);
}

.find-option-btn.active {
  background-color: var(--fr-btn-active-bg);
  color: var(--fr-btn-active);
}

.find-error-drawer {
  background-color: var(--fr-error-bg);
  border: 1px solid var(--fr-error-border);
  border-radius: 6px;
  padding: 6px 10px;
  font-size: 11px;
  color: var(--fr-text-danger);
  line-height: 1.3;
}

.find-replace-meta-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 2px 4px;
}

.find-match-count {
  font-size: 12px;
  color: var(--text-secondary);
}

.find-nav-group {
  display: flex;
  gap: 4px;
}

.find-nav-arrow-btn {
  background: none;
  border: 1px solid var(--fr-border);
  color: var(--text-color);
  font-size: 12px;
  cursor: pointer;
  padding: 2px 8px;
  border-radius: 4px;
  transition: background-color 0.15s ease;
  display: flex;
  align-items: center;
  justify-content: center;
}

.find-nav-arrow-btn:hover:not(:disabled) {
  background-color: var(--button-hover);
}

.find-nav-arrow-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.find-drawer-toggle-row {
  border-top: 1px solid var(--fr-border);
  margin-top: 4px;
  padding-top: 6px;
}

.drawer-toggle-btn {
  background: none;
  border: none;
  color: var(--text-secondary);
  font-size: 12px;
  cursor: pointer;
  display: flex;
  align-items: center;
  padding: 2px 4px;
  border-radius: 4px;
  transition: color 0.15s ease;
}

.drawer-toggle-btn:hover {
  color: var(--text-color);
}

.find-replace-drawer-content {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 4px 6px;
  border-top: 1px dashed var(--fr-border);
  margin-top: 2px;
  padding-top: 8px;
}

.drawer-field {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.drawer-field.check-field {
  flex-direction: row;
  align-items: center;
  gap: 6px;
  padding: 2px 0;
}

.drawer-label {
  font-size: 11px;
  font-weight: 600;
  color: var(--text-secondary);
}

.drawer-select {
  width: 100%;
  padding: 4px 6px;
  border-radius: 4px;
  border: 1px solid var(--fr-border);
  background-color: var(--bg-color);
  color: var(--text-color);
  font-size: 12px;
  outline: none;
}

.drawer-checkbox {
  margin: 0;
  cursor: pointer;
}

.drawer-label-checkbox {
  font-size: 12px;
  color: var(--text-color);
  cursor: pointer;
}

.find-replace-actions-footer {
  display: flex;
  gap: 6px;
  padding: 8px 12px 12px 12px;
  border-top: 1px solid var(--fr-border);
  background-color: var(--header-bg);
  border-bottom-left-radius: 11px;
  border-bottom-right-radius: 11px;
}

.find-replace-panel.docked .find-replace-actions-footer {
  border-bottom-left-radius: 0;
  border-bottom-right-radius: 0;
}

.fr-action-btn {
  flex: 1;
  padding: 6px 8px;
  font-size: 12px;
  font-weight: 500;
  border-radius: 6px;
  border: 1px solid var(--fr-border);
  background-color: var(--button-bg);
  color: var(--text-color);
  cursor: pointer;
  transition: background-color 0.15s ease, border-color 0.15s ease;
  text-align: center;
}

.fr-action-btn:hover:not(:disabled) {
  background-color: var(--button-hover);
}

.fr-action-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.fr-action-btn.secondary {
  max-width: 60px;
}

/* ========================================
   DIFF PREVIEW CONTAINER
   ======================================== */
.diff-preview-body {
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.diff-container {
  border: 1px solid var(--fr-border);
  border-radius: 8px;
  background-color: var(--bg-color);
  max-height: 400px;
  overflow: auto;
  font-family: 'SFMono-Regular', Consolas, 'Liberation Mono', Menlo, monospace;
  font-size: 12px;
  line-height: 1.5;
}

.diff-line {
  display: flex;
  padding: 1px 8px;
}

.diff-line.addition {
  background-color: rgba(46, 160, 67, 0.15);
  color: #3fb950;
}

.diff-line.deletion {
  background-color: rgba(248, 81, 73, 0.15);
  color: #f85149;
}

.diff-line.context {
  color: var(--text-secondary);
}

.diff-line-num {
  width: 40px;
  flex-shrink: 0;
  text-align: right;
  padding-right: 12px;
  border-right: 1px solid var(--fr-border);
  user-select: none;
  opacity: 0.5;
}

.diff-line-content {
  padding-left: 12px;
  white-space: pre-wrap;
  word-break: break-all;
}

/* ========================================
   DOCK LAYOUT CODES
   ======================================== */
.content-container {
  display: flex;
  flex: 1;
  overflow: hidden;
  position: relative;
}

.editor-dock-wrapper {
  display: flex;
  flex: 1;
  overflow: hidden;
  position: relative;
}

.editor-pane-inner {
  display: flex;
  flex-direction: column;
  flex: 1;
  position: relative;
  overflow: hidden;
}

/* ========================================
   MOBILE & TABLET FIND PANEL RESPONSIVE FIXES
   ======================================== */
@media (max-width: 1079px) {
  #find-replace-dock {
    display: none !important;
  }
}

@media (max-width: 768px) {
  /* Prevent full screen expansion of floating panel on small mobile viewports */
  .find-replace-panel {
    width: calc(100% - 24px) !important;
    right: 12px !important;
    left: 12px !important;
    top: 80px !important;
  }
}

/* ========================================
   SKELETON LOADING SHIMMER SYSTEM
   ======================================== */
.skeleton-placeholder {
  display: block;
  background-color: var(--skeleton-bg);
  border-radius: 6px;
  position: relative;
  overflow: hidden;
  /* PERF-017: Removed skeleton-pulse; shimmer-only is sufficient and halves GPU compositing layers */
  /* animation: skeleton-pulse 2.2s cubic-bezier(0.4, 0, 0.2, 1) infinite alternate; */
}

.skeleton-placeholder::after {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  transform: translateX(-100%);
  background-image: linear-gradient(
    90deg,
    rgba(255, 255, 255, 0) 0%,
    var(--skeleton-glow) 50%,
    rgba(255, 255, 255, 0) 100%
  );
  animation: skeleton-shimmer 1.6s cubic-bezier(0.4, 0, 0.2, 1) infinite;
}

@keyframes skeleton-shimmer {
  100% {
    transform: translateX(100%);
  }
}

@keyframes skeleton-pulse {
  0%, 100% {
    opacity: 1;
  }
  50% {
    opacity: 0.82;
  }
}

.skeleton-circle {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  margin: 0 auto;
}

.skeleton-text {
  height: 12px;
  width: 80%;
  margin: 4px auto;
  border-radius: 3px;
}

.skeleton-tree-folder {
  height: 16px;
  width: 140px;
  margin: 6px 0;
  display: inline-block;
}

.skeleton-tree-file {
  height: 14px;
  width: 180px;
  margin: 4px 0 4px 12px;
  display: inline-block;
}

/* Screen reader accessibility utility */
.visually-hidden {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  margin: -1px !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  clip-path: inset(50%) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

/* Article skeleton layout structures */
.skeleton-title {
  height: 28px;
  width: 35%;
  margin-bottom: 24px;
  border-radius: 8px;
}

.skeleton-subtitle {
  height: 20px;
  width: 20%;
  margin-bottom: 18px;
  margin-top: 32px;
  border-radius: 6px;
}

.skeleton-line {
  height: 14px;
  margin-bottom: 12px;
  border-radius: 6px;
}

/* Symmetrical dynamic widths */
.skeleton-w90 { width: 90%; }
.skeleton-w92 { width: 92%; }
.skeleton-w88 { width: 88%; }
.skeleton-w85 { width: 85%; }
.skeleton-w60 { width: 60%; }
.skeleton-w45 { width: 45%; }

/* Editor pane skeleton overlay */
.editor-skeleton {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  padding: 30px 24px 24px calc(24px + var(--line-number-gutter));
  z-index: 10;
  pointer-events: none;
  background: var(--editor-bg);
  box-sizing: border-box;
  overflow: hidden;
  transition: opacity 0.3s ease;
}

.editor-pane:not(.is-loading) .editor-skeleton {
  display: none;
}

.editor-pane.is-loading textarea {
  opacity: 0; /* Completely hide editor content while initial bootstrap skeleton runs */
}

/* Preview pane skeleton container */
.skeleton-preview-container {
  display: block;
  width: 100%;
  box-sizing: border-box;
  padding: 10px 4px;
  background: transparent;
  transition: opacity 0.3s ease;
}

/* Mermaid compilation loading states */
.mermaid-container.is-loading {
  min-height: 180px;
  background-color: var(--skeleton-bg);
  border-radius: 8px;
  border: 1px solid var(--border-color);
  position: relative;
  overflow: hidden;
  animation: skeleton-pulse 2.2s cubic-bezier(0.4, 0, 0.2, 1) infinite alternate;
}

.mermaid-container.is-loading .mermaid {
  opacity: 0; /* Hide raw chart source code during compile */
}

.mermaid-container.is-loading::after {
  content: "";
  position: absolute;
  inset: 0;
  transform: translateX(-100%);
  background-image: linear-gradient(
    90deg,
    rgba(255, 255, 255, 0) 0%,
    var(--skeleton-glow) 50%,
    rgba(255, 255, 255, 0) 100%
  );
  animation: skeleton-shimmer 1.6s cubic-bezier(0.4, 0, 0.2, 1) infinite;
}

/* --- ABC Notation Styles --- */
.abc-container {
  display: flex;
  flex-direction: column;
  align-items: center;
  margin: 1.5em 0;
  padding: 1.25em;
  background-color: var(--code-bg);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  overflow-x: auto;
  transition: background-color 0.2s ease, border-color 0.2s ease;
}

.abc-container.is-loading {
  min-height: 120px;
  background-color: var(--skeleton-bg);
  border-radius: 8px;
  border: 1px solid var(--border-color);
  position: relative;
  overflow: hidden;
  animation: skeleton-pulse 2.2s cubic-bezier(0.4, 0, 0.2, 1) infinite alternate;
}

.abc-container.is-loading .abc-notation {
  opacity: 0; /* Hide raw ABC text during compile */
}

.abc-container.is-loading::after {
  content: "";
  position: absolute;
  inset: 0;
  transform: translateX(-100%);
  background-image: linear-gradient(
    90deg,
    rgba(255, 255, 255, 0) 0%,
    var(--skeleton-glow) 50%,
    rgba(255, 255, 255, 0) 100%
  );
  animation: skeleton-shimmer 1.6s cubic-bezier(0.4, 0, 0.2, 1) infinite;
}

.abc-notation {
  width: 100%;
}

.abc-notation svg {
  background: transparent !important;
  color: var(--preview-text-color) !important;
  display: block;
  margin: 0 auto;
}

/* Theme Adaptation using currentColor */
.abc-notation svg path {
  fill: currentColor;
}

.abc-notation svg text {
  fill: currentColor !important;
  stroke: none !important;
}

.abc-notation svg .abcjs-staff,
.abc-notation svg .abcjs-staff-extra,
.abc-notation svg .abcjs-bar,
.abc-notation svg .abcjs-ledger,
.abc-notation svg .abcjs-stem,
.abc-notation svg .abcjs-beam,
.abc-notation svg .abcjs-slur,
.abc-notation svg .abcjs-tie {
  stroke: currentColor !important;
}

.abc-notation svg .abcjs-staff,
.abc-notation svg .abcjs-staff-extra,
.abc-notation svg .abcjs-ledger,
.abc-notation svg .abcjs-slur,
.abc-notation svg .abcjs-tie,
.abc-notation svg .abcjs-stem {
  fill: none !important;
}

/* Accessibility screen-reader-only element */
.abc-sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Accessibility: respect user's motion preferences */
@media (prefers-reduced-motion: reduce) {
  .skeleton-placeholder,
  .skeleton-placeholder::after,
  .mermaid-container.is-loading,
  .mermaid-container.is-loading::after,
  .abc-container.is-loading,
  .abc-container.is-loading::after {
    animation: none;
  }
  .drag-overlay-inner {
    animation: none;
  }
  .tab-item-new {
    animation: none;
  }
  body,
  .app-header,
  .editor-pane,
  .preview-pane,
  .tool-button,
  .markdown-tool-btn {
    transition: none;
  }
}