/* ============================================================
   RealtimeMD — Design System & Layout
   ============================================================ */

/* --- CSS Custom Properties (Design Tokens) --- */
:root {
  /* Colors — Dark Theme (default) */
  --color-bg-primary: #1e1e2e;
  --color-bg-secondary: #181825;
  --color-bg-tertiary: #11111b;
  --color-bg-surface: #252538;
  --color-bg-hover: #313244;
  --color-bg-active: #45475a;

  --color-text-primary: #cdd6f4;
  --color-text-secondary: #a6adc8;
  --color-text-muted: #6c7086;
  --color-text-accent: #89b4fa;

  --color-border: #313244;
  --color-border-focus: #89b4fa;

  --color-accent: #89b4fa;
  --color-accent-hover: #74c7ec;
  --color-accent-secondary: #cba6f7;
  --color-accent-green: #a6e3a1;
  --color-accent-red: #f38ba8;
  --color-accent-yellow: #f9e2af;
  --color-accent-peach: #fab387;

  /* Scrollbar */
  --color-scrollbar-track: transparent;
  --color-scrollbar-thumb: #45475a;
  --color-scrollbar-thumb-hover: #585b70;

  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 20px rgba(137, 180, 250, 0.15);

  /* Typography */
  --font-sans: 'Inter', 'Segoe UI', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Cascadia Code', 'Consolas', monospace;
  --font-size-xs: 0.6875rem;
  --font-size-sm: 0.8125rem;
  --font-size-base: 0.875rem;
  --font-size-md: 1rem;
  --font-size-lg: 1.25rem;
  --font-size-xl: 1.5rem;
  --font-size-2xl: 2rem;

  /* Spacing */
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 20px;
  --space-6: 24px;
  --space-8: 32px;

  /* Borders */
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;
  --radius-xl: 12px;
  --radius-full: 9999px;

  /* Transitions */
  --transition-fast: 120ms ease;
  --transition-base: 200ms ease;
  --transition-slow: 350ms cubic-bezier(0.4, 0, 0.2, 1);

  /* Layout */
  --sidebar-width: 260px;
  --ribbon-width: 48px;
  --toolbar-height: 40px;
  --statusbar-height: 28px;
  --header-height: 0px;
}

/* --- Light Theme --- */
[data-theme="light"] {
  --color-bg-primary: #eff1f5;
  --color-bg-secondary: #e6e9ef;
  --color-bg-tertiary: #dce0e8;
  --color-bg-surface: #ffffff;
  --color-bg-hover: #ccd0da;
  --color-bg-active: #bcc0cc;

  --color-text-primary: #4c4f69;
  --color-text-secondary: #5c5f77;
  --color-text-muted: #8c8fa1;
  --color-text-accent: #1e66f5;

  --color-border: #ccd0da;
  --color-border-focus: #1e66f5;

  --color-accent: #1e66f5;
  --color-accent-hover: #2a6ef6;
  --color-accent-secondary: #8839ef;
  --color-accent-green: #40a02b;
  --color-accent-red: #d20f39;
  --color-accent-yellow: #df8e1d;
  --color-accent-peach: #fe640b;

  --color-scrollbar-thumb: #bcc0cc;
  --color-scrollbar-thumb-hover: #acb0be;

  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.12);
  --shadow-glow: 0 0 20px rgba(30, 102, 245, 0.1);
}

/* --- Reset & Base --- */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  color: var(--color-text-primary);
  background: var(--color-bg-tertiary);
  line-height: 1.5;
  overflow: hidden;
  height: 100vh;
  width: 100vw;
}

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

a:hover {
  text-decoration: underline;
}

/* --- Scrollbar --- */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

::-webkit-scrollbar-track {
  background: var(--color-scrollbar-track);
}

::-webkit-scrollbar-thumb {
  background: var(--color-scrollbar-thumb);
  border-radius: var(--radius-full);
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-scrollbar-thumb-hover);
}

/* --- App Shell --- */
#app {
  display: flex;
  flex-direction: column;
  height: 100vh;
  width: 100vw;
  overflow: hidden;
}

/* --- Toolbar --- */
.toolbar {
  display: flex;
  align-items: center;
  height: var(--toolbar-height);
  background: var(--color-bg-secondary);
  border-bottom: 1px solid var(--color-border);
  padding: 0 var(--space-2);
  gap: var(--space-1);
  flex-shrink: 0;
  z-index: 100;
}

.toolbar-group {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.toolbar-separator {
  width: 1px;
  height: 20px;
  background: var(--color-border);
  margin: 0 var(--space-2);
}

.toolbar-spacer {
  flex: 1;
}

.toolbar-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 30px;
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-text-secondary);
  cursor: pointer;
  transition: all var(--transition-fast);
  position: relative;
}

.toolbar-btn:hover {
  background: var(--color-bg-hover);
  color: var(--color-text-primary);
}

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

.toolbar-btn.active {
  color: var(--color-accent);
  background: rgba(137, 180, 250, 0.1);
}

.toolbar-btn svg {
  width: 16px;
  height: 16px;
}

.toolbar-btn[data-tooltip]::after {
  content: attr(data-tooltip);
  position: absolute;
  bottom: -30px;
  left: 50%;
  transform: translateX(-50%);
  padding: 3px 8px;
  background: var(--color-bg-tertiary);
  color: var(--color-text-primary);
  font-size: var(--font-size-xs);
  border-radius: var(--radius-sm);
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-fast);
  z-index: 1000;
  border: 1px solid var(--color-border);
}

.toolbar-btn[data-tooltip]:hover::after {
  opacity: 1;
}

/* --- Main Layout --- */
.main-container {
  display: flex;
  flex: 1;
  overflow: hidden;
  position: relative;
}

/* --- Ribbon (Activity Bar) --- */
.ribbon {
  display: flex;
  flex-direction: column;
  width: var(--ribbon-width);
  background: var(--color-bg-tertiary);
  border-right: 1px solid var(--color-border);
  flex-shrink: 0;
  z-index: 50;
}

.ribbon-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: var(--ribbon-width);
  height: var(--ribbon-width);
  border: none;
  background: transparent;
  color: var(--color-text-muted);
  cursor: pointer;
  transition: all var(--transition-fast);
  position: relative;
}

.ribbon-btn::before {
  content: '';
  position: absolute;
  left: 0;
  top: 25%;
  bottom: 25%;
  width: 2px;
  background: transparent;
  border-radius: 0 2px 2px 0;
  transition: background var(--transition-fast);
}

.ribbon-btn:hover {
  color: var(--color-text-primary);
}

.ribbon-btn.active {
  color: var(--color-text-primary);
}

.ribbon-btn.active::before {
  background: var(--color-accent);
}

.ribbon-btn svg {
  width: 24px;
  height: 24px;
}

.ribbon-bottom {
  margin-top: auto;
}

/* --- Sidebar --- */
.sidebar {
  width: 0;
  min-width: 0;
  background: var(--color-bg-secondary);
  border-right: 1px solid var(--color-border);
  overflow: hidden;
  transition: width var(--transition-slow), min-width var(--transition-slow);
  display: flex;
  flex-direction: column;
  flex-shrink: 0;
  z-index: 40;
}

.sidebar.open {
  width: var(--sidebar-width);
  min-width: var(--sidebar-width);
}

.sidebar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-3) var(--space-4);
  font-size: var(--font-size-xs);
  text-transform: uppercase;
  color: var(--color-text-muted);
  letter-spacing: 0.08em;
  font-weight: 600;
  white-space: nowrap;
}

.sidebar-header-actions {
  display: flex;
  gap: var(--space-1);
}

.sidebar-header-actions button {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 22px;
  height: 22px;
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-text-muted);
  cursor: pointer;
}

.sidebar-header-actions button:hover {
  background: var(--color-bg-hover);
  color: var(--color-text-primary);
}

.sidebar-header-actions button svg {
  width: 14px;
  height: 14px;
}

.sidebar-content {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
}

/* --- File Tree --- */
.file-tree {
  font-size: var(--font-size-sm);
  user-select: none;
}

.file-tree-item {
  display: flex;
  align-items: center;
  padding: 3px var(--space-4);
  padding-left: calc(var(--space-4) + var(--depth, 0) * 16px);
  cursor: pointer;
  white-space: nowrap;
  gap: var(--space-2);
  color: var(--color-text-secondary);
  transition: background var(--transition-fast);
  position: relative;
}

.file-tree-item:hover {
  background: var(--color-bg-hover);
}

.file-tree-item.active {
  background: var(--color-bg-active);
  color: var(--color-text-primary);
}

.file-tree-item.active::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--color-accent);
}

.file-tree-item svg {
  width: 16px;
  height: 16px;
  flex-shrink: 0;
}

.file-tree-item .chevron {
  width: 12px;
  height: 12px;
  transition: transform var(--transition-fast);
}

.file-tree-item .chevron.expanded {
  transform: rotate(90deg);
}

.file-tree-item .file-icon {
  color: var(--color-accent);
}

.file-tree-item .folder-icon {
  color: var(--color-accent-peach);
}

.file-tree-item .image-icon {
  color: var(--color-accent-green);
}

.file-tree-item-name {
  overflow: hidden;
  text-overflow: ellipsis;
}

.file-tree-item-actions {
  display: none;
  margin-left: auto;
  gap: var(--space-1);
}

.file-tree-item:hover .file-tree-item-actions {
  display: flex;
}

.file-tree-item-actions button {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 20px;
  height: 20px;
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-text-muted);
  cursor: pointer;
}

.file-tree-item-actions button:hover {
  background: var(--color-bg-active);
  color: var(--color-text-primary);
}

.file-tree-item-actions button svg {
  width: 12px;
  height: 12px;
}

/* Rename input */
.file-tree-rename-input {
  background: var(--color-bg-surface);
  border: 1px solid var(--color-border-focus);
  border-radius: var(--radius-sm);
  color: var(--color-text-primary);
  font-size: var(--font-size-sm);
  font-family: var(--font-sans);
  padding: 1px 4px;
  outline: none;
  width: 100%;
  flex: 1;
  min-width: 0;
}

.file-tree-rename-input:focus {
  box-shadow: 0 0 0 1px var(--color-accent);
}

/* Empty state */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--space-8) var(--space-4);
  text-align: center;
  gap: var(--space-3);
}

/* --- Editor Area --- */
.workspace {
  flex: 1;
  display: flex;
  overflow: hidden;
}

/* PC: side-by-side */
.editor-preview-container {
  flex: 1;
  display: flex;
  flex-direction: row;
  overflow: hidden;
}

.editor-pane,
.preview-pane {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  min-width: 0;
}

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

/* Pane header */
.pane-header {
  display: flex;
  align-items: center;
  height: 32px;
  padding: 0 var(--space-4);
  background: var(--color-bg-secondary);
  border-bottom: 1px solid var(--color-border);
  font-size: var(--font-size-xs);
  color: var(--color-text-muted);
  text-transform: uppercase;
  letter-spacing: 0.06em;
  flex-shrink: 0;
}

.pane-header .file-name {
  color: var(--color-text-secondary);
  text-transform: none;
  letter-spacing: 0;
  font-size: var(--font-size-sm);
  margin-left: var(--space-2);
}

.pane-header .unsaved-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--color-accent-peach);
  margin-left: var(--space-2);
  display: none;
}

.pane-header .unsaved-dot.visible {
  display: block;
}

/* Resize handle */
.resize-handle {
  width: 4px;
  cursor: col-resize;
  background: transparent;
  transition: background var(--transition-fast);
  flex-shrink: 0;
  z-index: 10;
}

.resize-handle:hover,
.resize-handle.active {
  background: var(--color-accent);
}

/* --- Find/Replace Bar --- */
.find-replace-bar {
  display: none;
  /* hidden by default; HTML hidden attr */
  background: var(--color-bg-secondary);
  border-bottom: 1px solid var(--color-border);
  padding: 4px 8px;
  flex-direction: column;
  gap: 4px;
  z-index: 10;
}

.find-replace-bar:not([hidden]) {
  display: flex;
  /* only show when hidden attr is removed */
}

.fr-row {
  display: flex;
  align-items: center;
  gap: 4px;
}

.fr-input {
  flex: 1;
  min-width: 0;
  padding: 3px 8px;
  border: 1px solid var(--color-border);
  border-radius: 3px;
  background: var(--color-bg-primary);
  color: var(--color-text-primary);
  font-family: var(--font-mono);
  font-size: 13px;
  outline: none;
}

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

.fr-count {
  font-size: 12px;
  color: var(--color-text-muted);
  white-space: nowrap;
  min-width: 60px;
  text-align: center;
}

.fr-count.fr-error {
  color: #e74c3c;
}

.fr-btn {
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: 3px;
  color: var(--color-text-secondary);
  cursor: pointer;
  padding: 2px 6px;
  font-size: 12px;
  line-height: 1.4;
  display: flex;
  align-items: center;
  justify-content: center;
}

.fr-btn:hover {
  background: var(--color-bg-hover);
  color: var(--color-text-primary);
}

.fr-close-btn {
  margin-left: auto;
}

.fr-action-btn {
  font-size: 12px;
  padding: 2px 10px;
}

.fr-toggles {
  display: flex;
  gap: 2px;
}

.fr-toggle {
  display: flex;
  align-items: center;
  gap: 0;
  cursor: pointer;
  font-size: 11px;
  color: var(--color-text-muted);
  border: 1px solid transparent;
  border-radius: 3px;
  padding: 1px 4px;
}

.fr-toggle:has(input:checked) {
  background: var(--color-accent);
  color: #fff;
  border-color: var(--color-accent);
}

.fr-toggle input {
  position: absolute;
  opacity: 0;
  width: 0;
  height: 0;
}

/* --- Find/Replace Highlight Overlay --- */
.find-highlight-overlay {
  position: absolute;
  top: 0;
  left: 48px;
  /* same as line-numbers width */
  right: 0;
  bottom: 0;
  pointer-events: none;
  overflow: hidden;
  padding: var(--space-3) var(--space-4);
  font-family: var(--font-mono);
  font-size: var(--font-size-sm);
  line-height: 1.65;
  white-space: pre-wrap;
  word-wrap: break-word;
  color: transparent;
  z-index: 0;
}

.editor-textarea {
  position: relative;
  z-index: 1;
  background: transparent !important;
}


mark.fr-match {
  background: rgba(255, 213, 79, 0.45);
  color: transparent;
  border-radius: 2px;
}

mark.fr-current {
  background: rgba(255, 152, 0, 0.7);
  outline: 2px solid var(--color-accent);
  outline-offset: -1px;
}

/* --- Editor --- */
.editor-wrapper {
  flex: 1;
  display: flex;
  overflow: hidden;
  position: relative;
  background: var(--color-bg-primary);
}

.line-numbers {
  width: 48px;
  padding: var(--space-3) var(--space-2);
  text-align: right;
  background: var(--color-bg-primary);
  color: var(--color-text-muted);
  font-family: var(--font-mono);
  font-size: var(--font-size-sm);
  line-height: 1.65;
  overflow: hidden;
  user-select: none;
  flex-shrink: 0;
  border-right: 1px solid var(--color-border);
}

.line-numbers .line-num {
  display: block;
  height: 1.65em;
}

.editor-textarea {
  flex: 1;
  resize: none;
  border: none;
  outline: none;
  padding: var(--space-3) var(--space-4);
  background: var(--color-bg-primary);
  color: var(--color-text-primary);
  font-family: var(--font-mono);
  font-size: var(--font-size-sm);
  line-height: 1.65;
  tab-size: 2;
  -moz-tab-size: 2;
  white-space: pre-wrap;
  word-wrap: break-word;
  overflow-y: auto;
}

.editor-textarea::placeholder {
  color: var(--color-text-muted);
}

.editor-textarea:focus {
  box-shadow: none;
}

/* --- Preview --- */
.preview-wrapper {
  flex: 1;
  overflow-y: auto;
  padding: var(--space-6);
  background: var(--color-bg-primary);
}

/* Markdown rendered content */
.preview-content {
  max-width: 800px;
  margin: 0 auto;
  color: var(--color-text-primary);
  font-size: var(--font-size-base);
  line-height: 1.75;
}

.preview-content h1 {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  margin: 1.5em 0 0.5em;
  padding-bottom: 0.3em;
  border-bottom: 1px solid var(--color-border);
  color: var(--color-text-primary);
}

.preview-content h2 {
  font-size: var(--font-size-xl);
  font-weight: 600;
  margin: 1.3em 0 0.4em;
  padding-bottom: 0.2em;
  border-bottom: 1px solid var(--color-border);
  color: var(--color-text-primary);
}

.preview-content h3 {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin: 1.2em 0 0.3em;
  color: var(--color-text-primary);
}

.preview-content h4,
.preview-content h5,
.preview-content h6 {
  font-size: var(--font-size-md);
  font-weight: 600;
  margin: 1em 0 0.3em;
  color: var(--color-text-primary);
}

.preview-content p {
  margin: 0.6em 0;
}

.preview-content a {
  color: var(--color-accent);
  text-decoration: underline;
}

.preview-content strong {
  font-weight: 600;
  color: var(--color-text-primary);
}

.preview-content em {
  font-style: italic;
}

.preview-content code {
  font-family: var(--font-mono);
  font-size: 0.85em;
  padding: 0.15em 0.4em;
  background: var(--color-bg-surface);
  border-radius: var(--radius-sm);
  color: var(--color-accent-peach);
}

.preview-content pre {
  margin: 1em 0;
  padding: var(--space-4);
  background: var(--color-bg-tertiary);
  border-radius: var(--radius-md);
  overflow-x: auto;
  border: 1px solid var(--color-border);
}

.preview-content pre code {
  padding: 0;
  background: none;
  color: var(--color-text-primary);
  font-size: var(--font-size-sm);
}

.preview-content blockquote {
  margin: 1em 0;
  padding: var(--space-3) var(--space-4);
  border-left: 3px solid var(--color-accent);
  background: var(--color-bg-surface);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: var(--color-text-secondary);
}

.preview-content blockquote p {
  margin: 0.3em 0;
}

.preview-content ul,
.preview-content ol {
  margin: 0.6em 0;
  padding-left: 1.8em;
}

.preview-content li {
  margin: 0.25em 0;
}

.preview-content li input[type="checkbox"] {
  margin-right: var(--space-2);
  accent-color: var(--color-accent);
}

.preview-content hr {
  border: none;
  height: 1px;
  background: var(--color-border);
  margin: 1.5em 0;
}

.preview-content img {
  max-width: 100%;
  border-radius: var(--radius-md);
  margin: 0.5em 0;
}

.preview-content table {
  border-collapse: collapse;
  width: 100%;
  margin: 1em 0;
}

.preview-content table th,
.preview-content table td {
  border: 1px solid var(--color-border);
  padding: var(--space-2) var(--space-3);
  text-align: left;
}

.preview-content table th {
  background: var(--color-bg-surface);
  font-weight: 600;
}

.preview-content table tr:nth-child(even) {
  background: var(--color-bg-surface);
}

/* --- Status Bar --- */
.statusbar {
  display: flex;
  align-items: center;
  height: var(--statusbar-height);
  background: var(--color-accent);
  padding: 0 var(--space-3);
  font-size: var(--font-size-xs);
  color: #fff;
  flex-shrink: 0;
  gap: var(--space-4);
  z-index: 100;
}

.statusbar-item {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  white-space: nowrap;
}

.statusbar-spacer {
  flex: 1;
}

.statusbar-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: 2px var(--space-2);
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: #fff;
  font-size: var(--font-size-xs);
  cursor: pointer;
  font-family: var(--font-sans);
}

.statusbar-btn:hover {
  background: rgba(255, 255, 255, 0.15);
}

/* --- Dialogs / Modals --- */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--transition-base);
  backdrop-filter: blur(4px);
}

.modal-overlay.visible {
  opacity: 1;
  pointer-events: auto;
}

.modal {
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-6);
  min-width: 320px;
  max-width: 500px;
  width: 90vw;
  box-shadow: var(--shadow-lg);
  transform: translateY(10px);
  transition: transform var(--transition-base);
}

.modal-overlay.visible .modal {
  transform: translateY(0);
}

.modal-title {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: var(--space-4);
  color: var(--color-text-primary);
}

.modal-body {
  color: var(--color-text-secondary);
  margin-bottom: var(--space-6);
  font-size: var(--font-size-base);
  line-height: 1.6;
}

.modal-actions {
  display: flex;
  justify-content: flex-end;
  gap: var(--space-3);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-bg-surface);
  color: var(--color-text-primary);
  font-size: var(--font-size-sm);
  font-family: var(--font-sans);
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
}

.btn:hover {
  background: var(--color-bg-hover);
}

.btn-primary {
  background: var(--color-accent);
  border-color: var(--color-accent);
  color: #fff;
}

.btn-primary:hover {
  background: var(--color-accent-hover);
  border-color: var(--color-accent-hover);
}

.btn-danger {
  border-color: var(--color-accent-red);
  color: var(--color-accent-red);
}

.btn-danger:hover {
  background: var(--color-accent-red);
  color: #fff;
}

/* --- Context Menu --- */
.context-menu {
  position: fixed;
  background: var(--color-bg-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: var(--space-1) 0;
  min-width: 180px;
  box-shadow: var(--shadow-lg);
  z-index: 10000;
  display: none;
}

.context-menu.visible {
  display: block;
}

.context-menu-item {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-2) var(--space-4);
  cursor: pointer;
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  transition: background var(--transition-fast);
}

.context-menu-item:hover {
  background: var(--color-bg-hover);
  color: var(--color-text-primary);
}

.context-menu-item.danger {
  color: var(--color-accent-red);
}

.context-menu-separator {
  height: 1px;
  background: var(--color-border);
  margin: var(--space-1) 0;
}

/* --- Drop Zone --- */
.drop-zone-overlay {
  position: fixed;
  inset: 0;
  background: rgba(137, 180, 250, 0.08);
  border: 2px dashed var(--color-accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: var(--font-size-lg);
  color: var(--color-accent);
  z-index: 9998;
  pointer-events: none;
  opacity: 0;
  transition: opacity var(--transition-fast);
}

.drop-zone-overlay.visible {
  opacity: 1;
}

/* --- Toast Notifications --- */
.toast-container {
  position: fixed;
  bottom: calc(var(--statusbar-height) + var(--space-4));
  right: var(--space-4);
  display: flex;
  flex-direction: column-reverse;
  gap: var(--space-2);
  z-index: 9999;
}

.toast {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  background: var(--color-bg-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-md);
  font-size: var(--font-size-sm);
  color: var(--color-text-primary);
  animation: toast-in 0.3s ease forwards;
  max-width: 360px;
}

.toast.success {
  border-left: 3px solid var(--color-accent-green);
}

.toast.error {
  border-left: 3px solid var(--color-accent-red);
}

.toast.info {
  border-left: 3px solid var(--color-accent);
}

.toast-removing {
  animation: toast-out 0.2s ease forwards;
}

@keyframes toast-in {
  from {
    opacity: 0;
    transform: translateX(30px);
  }

  to {
    opacity: 1;
    transform: translateX(0);
  }
}

@keyframes toast-out {
  from {
    opacity: 1;
    transform: translateX(0);
  }

  to {
    opacity: 0;
    transform: translateX(30px);
  }
}

/* --- Empty State --- */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  height: 100%;
  color: var(--color-text-muted);
  text-align: center;
  gap: var(--space-3);
  padding: var(--space-6);
}

.empty-state svg {
  width: 48px;
  height: 48px;
  opacity: 0.3;
}

.empty-state p {
  font-size: var(--font-size-sm);
  max-width: 260px;
}

/* --- Mobile (Responsive) --- */
@media (max-width: 767px) {
  .ribbon {
    display: none;
  }

  .sidebar {
    position: fixed;
    left: 0;
    top: var(--toolbar-height);
    bottom: var(--statusbar-height);
    width: 0;
    z-index: 200;
    box-shadow: var(--shadow-lg);
  }

  .sidebar.open {
    width: 85vw;
    max-width: 320px;
  }

  /* Overlay behind sidebar on mobile */
  .sidebar-backdrop {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.5);
    z-index: 199;
    display: none;
  }

  .sidebar-backdrop.visible {
    display: block;
  }

  .editor-preview-container {
    flex-direction: column-reverse;
  }

  .editor-pane {
    border-right: none;
    border-top: 1px solid var(--color-border);
  }

  .resize-handle {
    display: none;
  }

  .line-numbers {
    width: 36px;
  }

  .toolbar-btn[data-tooltip]::after {
    display: none;
  }

  .preview-wrapper {
    padding: var(--space-4);
  }

  /* Mobile toolbar extras */
  .mobile-menu-btn {
    display: flex !important;
  }

  .desktop-only {
    display: none !important;
  }

  /* Show mobile action bar */
  .mobile-action-bar {
    display: flex !important;
  }

  /* Add bottom padding so mobile action bar doesn't cover content */
  .statusbar {
    margin-bottom: calc(44px + env(safe-area-inset-bottom, 0px));
  }

  .editor-pane,
  .preview-pane {
    padding-bottom: calc(44px + env(safe-area-inset-bottom, 0px));
  }
}

@media (min-width: 768px) {
  .mobile-menu-btn {
    display: none !important;
  }

  .sidebar-backdrop {
    display: none !important;
  }

  .mobile-only {
    display: none !important;
  }

  .mobile-action-bar {
    display: none !important;
  }
}

/* --- Utility --- */
.hidden {
  display: none !important;
}

.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;
}

/* --- Extension Slots --- */
.extension-slot {
  display: none;
}

.extension-slot.active {
  display: block;
}

/* --- Loading Shimmer --- */
@keyframes shimmer {
  0% {
    background-position: -200% 0;
  }

  100% {
    background-position: 200% 0;
  }
}

.loading-shimmer {
  background: linear-gradient(90deg,
      var(--color-bg-surface) 25%,
      var(--color-bg-hover) 50%,
      var(--color-bg-surface) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
  border-radius: var(--radius-sm);
}

/* --- Language Selector (Ribbon) --- */
.ribbon-lang-select {
  appearance: none;
  -webkit-appearance: none;
  background: transparent;
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-xs);
  font-family: var(--font-sans);
  padding: 2px 4px;
  cursor: pointer;
  text-align: center;
  width: 38px;
  margin: 0 auto;
  transition: color var(--transition-fast), border-color var(--transition-fast);
}

.ribbon-lang-select:hover {
  color: var(--color-text-primary);
  border-color: var(--color-accent);
}

.ribbon-lang-select:focus {
  outline: none;
  border-color: var(--color-accent);
}

.ribbon-lang-select option {
  background: var(--color-bg-secondary);
  color: var(--color-text-primary);
}

/* --- Print Stylesheet (PDF Export) --- */
@media print {

  @page {
    margin: 12mm;
  }

  /* Hide everything except the preview content */
  .toolbar,
  .ribbon,
  .sidebar,
  .sidebar-backdrop,
  .editor-pane,
  .resize-handle,
  .statusbar,
  .drop-zone-overlay,
  .toast-container,
  .context-menu,
  .extension-slot,
  .pane-header,
  #btn-mobile-menu {
    display: none !important;
  }

  /* CRITICAL: Reset layout constraints that cause single-page truncation */
  html,
  body {
    height: auto !important;
    max-height: none !important;
    overflow: visible !important;
    background: white !important;
    color: black !important;
    margin: 0;
    padding: 0;
  }

  #app {
    display: block !important;
    height: auto !important;
    overflow: visible !important;
  }

  .main-container {
    display: block !important;
    height: auto !important;
    overflow: visible !important;
    padding: 0 !important;
  }

  .workspace {
    display: block !important;
    height: auto !important;
    overflow: visible !important;
    margin: 0 !important;
    padding: 0 !important;
  }

  .editor-preview-container {
    display: block !important;
    height: auto !important;
    overflow: visible !important;
  }

  .preview-pane {
    display: block !important;
    flex: unset !important;
    width: 100% !important;
    height: auto !important;
    max-height: none !important;
    overflow: visible !important;
    border: none !important;
    position: static !important;
  }

  .preview-wrapper {
    overflow: visible !important;
    height: auto !important;
    max-height: none !important;
    position: static !important;
  }

  .preview-content {
    padding: 20px !important;
    max-width: 100% !important;
    color: black !important;
    background: white !important;
    font-size: 12pt !important;
    line-height: 1.6 !important;
  }

  .preview-content h1,
  .preview-content h2,
  .preview-content h3 {
    color: #111 !important;
  }

  .preview-content a {
    color: #1e66f5 !important;
    text-decoration: underline !important;
  }

  .preview-content code {
    background: #f0f0f0 !important;
    color: #333 !important;
    border: 1px solid #ddd !important;
  }

  .preview-content pre {
    background: #f5f5f5 !important;
    border: 1px solid #ddd !important;
    page-break-inside: avoid;
  }

  .preview-content pre code {
    border: none !important;
  }

  .preview-content blockquote {
    border-left-color: #999 !important;
    color: #555 !important;
  }

  .preview-content img {
    max-width: 100% !important;
    page-break-inside: avoid;
  }

  .preview-content table {
    border-collapse: collapse !important;
  }

  .preview-content th,
  .preview-content td {
    border: 1px solid #ccc !important;
    color: #333 !important;
  }

  .preview-content th {
    background: #f0f0f0 !important;
  }

  /* Print: show mermaid SVGs and MathJax output */
  .preview-content .mermaid svg {
    max-width: 100% !important;
    page-break-inside: avoid;
  }

  .preview-content .math-display,
  .preview-content .math-inline {
    color: black !important;
  }

  /* Hide mobile action bar in print */
  .mobile-action-bar {
    display: none !important;
  }

  /* Hide dialog overlay in print */
  .dialog-overlay {
    display: none !important;
  }
}

/* --- Mobile Action Bar --- */
.mobile-action-bar {
  display: none;
  /* Hidden by default; shown via media query on mobile */
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  height: 44px;
  padding-bottom: env(safe-area-inset-bottom, 0px);
  background: var(--color-bg-secondary);
  border-top: 1px solid var(--color-border);
  z-index: 300;
  align-items: center;
  justify-content: space-around;
  gap: var(--space-1);
}

.mob-action-btn {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1px;
  background: none;
  border: none;
  color: var(--color-text-secondary);
  cursor: pointer;
  padding: 4px 8px;
  font-size: 9px;
  font-family: var(--font-sans);
  transition: color var(--transition-fast);
  -webkit-tap-highlight-color: transparent;
}

.mob-action-btn:active {
  color: var(--color-accent);
}

.mob-action-btn svg {
  flex-shrink: 0;
}

.mob-lang-select {
  appearance: none;
  -webkit-appearance: none;
  background: transparent;
  color: var(--color-text-secondary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: 10px;
  font-family: var(--font-sans);
  padding: 2px 4px;
  cursor: pointer;
  text-align: center;
  width: 36px;
}

.mob-lang-select option {
  background: var(--color-bg-secondary);
  color: var(--color-text-primary);
}

/* --- Dialog Overlay --- */
.dialog-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  backdrop-filter: blur(4px);
  z-index: 1000;
  align-items: center;
  justify-content: center;
}

.dialog-overlay.visible {
  display: flex;
}

/* --- Help Panel --- */
.help-panel {
  background: var(--color-bg-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 0;
  max-width: 520px;
  width: 90vw;
  max-height: 80vh;
  box-shadow: var(--shadow-lg);
  display: flex;
  flex-direction: column;
}

.help-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-4) var(--space-5);
  border-bottom: 1px solid var(--color-border);
}

.help-header h3 {
  margin: 0;
  font-size: var(--font-size-lg);
  color: var(--color-text-primary);
}

.help-close-btn {
  background: none;
  border: none;
  font-size: 1.4em;
  cursor: pointer;
  color: var(--color-text-muted);
  padding: 4px 8px;
  border-radius: var(--radius-sm);
}

.help-close-btn:hover {
  color: var(--color-text-primary);
  background: var(--color-bg-hover);
}

.help-body {
  padding: var(--space-4) var(--space-5);
  overflow-y: auto;
  color: var(--color-text-primary);
  font-size: var(--font-size-sm);
  line-height: 1.6;
}

.help-body section {
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-3);
  border-bottom: 1px solid var(--color-border);
}

.help-body section:last-child {
  border-bottom: none;
  margin-bottom: 0;
}

.help-body h4 {
  margin: 0 0 var(--space-2) 0;
  color: var(--color-text-primary);
  font-size: var(--font-size-base);
}

.help-body p {
  margin: var(--space-1) 0;
  color: var(--color-text-secondary);
}

.help-body small {
  color: var(--color-text-muted);
}

.help-body pre {
  background: var(--color-bg-primary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  padding: var(--space-3);
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 12px;
  line-height: 1.5;
  color: var(--color-text-primary);
}

.help-body code {
  font-family: var(--font-mono);
  font-size: 12px;
}

.dialog-box {
  background: var(--color-bg-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  max-width: 420px;
  width: 90vw;
  box-shadow: var(--shadow-lg);
}

.dialog-box h3 {
  margin: 0 0 var(--space-3) 0;
  font-size: var(--font-size-lg);
  color: var(--color-text-primary);
  font-weight: 600;
}

.dialog-box p {
  margin: 0 0 var(--space-5) 0;
  font-size: var(--font-size-sm);
  color: var(--color-text-secondary);
  line-height: 1.5;
}

.dialog-actions {
  display: flex;
  justify-content: flex-end;
  gap: var(--space-3);
}

.dialog-btn {
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-md);
  font-size: var(--font-size-sm);
  font-family: var(--font-sans);
  cursor: pointer;
  border: 1px solid var(--color-border);
  transition: all var(--transition-fast);
}

.dialog-btn-cancel {
  background: var(--color-bg-hover);
  color: var(--color-text-primary);
}

.dialog-btn-cancel:hover {
  background: var(--color-bg-active);
}

.dialog-btn-danger {
  background: var(--color-accent-red);
  color: #fff;
  border-color: var(--color-accent-red);
}

.dialog-btn-danger:hover {
  opacity: 0.9;
}

/* --- Mermaid Diagrams --- */
.preview-content .mermaid {
  text-align: center;
  margin: var(--space-4) 0;
  padding: var(--space-3);
  background: var(--color-bg-surface);
  border-radius: var(--radius-md);
  overflow-x: auto;
}

.preview-content .mermaid svg {
  max-width: 100%;
  height: auto;
}

.preview-content .mermaid-error {
  color: var(--color-accent-red);
  font-size: var(--font-size-sm);
  background: var(--color-bg-surface);
  padding: var(--space-3);
  border-radius: var(--radius-sm);
  border: 1px solid var(--color-accent-red);
  white-space: pre-wrap;
}

/* --- Math Blocks --- */
.preview-content .math-display {
  text-align: center;
  margin: var(--space-4) 0;
  overflow-x: auto;
}

/* Math inline styling handled by MathJax */