/* ── Variables ──────────────────────────────────────────────────────────────── */

:root {
  --bg:          #ffffff;
  --bg-toolbar:  #f6f8fa;
  --bg-preview:  #ffffff;
  --border:      #d0d7de;
  --text:        #1f2328;
  --text-muted:  #656d76;
  --btn-hover:   #e7eaf0;
  --divider:     #d0d7de;
  --divider-w:   5px;
  --toolbar-h:   42px;
  --status-h:    28px;
  --font-ui:     -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  --font-editor: "JetBrains Mono", "Fira Code", "Cascadia Code", monospace;
  --radius:      6px;
}

[data-theme="dark"] {
  --bg:         #0d1117;
  --bg-toolbar: #161b22;
  --bg-preview: #0d1117;
  --border:     #30363d;
  --text:       #e6edf3;
  --text-muted: #848d97;
  --btn-hover:  #21262d;
  --divider:    #30363d;
}

/* ── Reset / Base ────────────────────────────────────────────────────────────── */

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

html, body {
  height: 100%;
  overflow: hidden;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-ui);
  font-size: 14px;
}

/* ── App shell ───────────────────────────────────────────────────────────────── */

#app {
  display: flex;
  flex-direction: column;
  height: 100vh;
}

/* ── Toolbar ─────────────────────────────────────────────────────────────────── */

#toolbar {
  display: flex;
  align-items: center;
  gap: 2px;
  height: var(--toolbar-h);
  padding: 0 10px;
  background: var(--bg-toolbar);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
  overflow-x: auto;
  scrollbar-width: none;
}
#toolbar::-webkit-scrollbar { display: none; }

.toolbar-group {
  display: flex;
  align-items: center;
  gap: 1px;
}

.toolbar-sep {
  width: 1px;
  height: 20px;
  background: var(--border);
  margin: 0 4px;
  flex-shrink: 0;
}

.toolbar-spacer { flex: 1; }

#toolbar button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 28px;
  padding: 0 8px;
  border: none;
  background: transparent;
  color: var(--text);
  font-family: var(--font-ui);
  font-size: 12.5px;
  border-radius: var(--radius);
  cursor: pointer;
  white-space: nowrap;
  transition: background 0.1s;
}

#toolbar button:hover  { background: var(--btn-hover); }
#toolbar button:active { opacity: 0.7; }

/* ── Panes ───────────────────────────────────────────────────────────────────── */

#panes {
  display: flex;
  flex: 1;
  overflow: hidden;
}

#editor-pane {
  flex: 1;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

/* CodeMirror fills the pane */
#editor-pane .cm-editor {
  height: 100%;
  font-family: var(--font-editor);
  font-size: 14px;
}

#editor-pane .cm-scroller {
  overflow: auto;
  height: 100%;
  padding: 16px 0;
}

#editor-pane .cm-content {
  padding: 0 20px;
  max-width: 100%;
}

/* Remove CM default focus outline */
#editor-pane .cm-focused { outline: none; }

/* ── Divider ─────────────────────────────────────────────────────────────────── */

#divider {
  width: var(--divider-w);
  background: var(--border);
  cursor: col-resize;
  flex-shrink: 0;
  transition: background 0.15s;
}

#divider:hover { background: #4493f8; }

/* ── Preview pane ────────────────────────────────────────────────────────────── */

#preview-pane {
  flex: 1;
  overflow-y: auto;
  background: var(--bg-preview);
  padding: 24px 32px;
}

/* github-markdown-css root */
#preview.markdown-body {
  max-width: 820px;
  margin: 0 auto;
  background: transparent;
  font-size: 15px;
  line-height: 1.7;
  color: var(--text);
}

/* Override github-markdown-css backgrounds to respect our theme */
[data-theme="dark"] #preview.markdown-body {
  color-scheme: dark;
}

[data-theme="dark"] #preview.markdown-body pre,
[data-theme="dark"] #preview.markdown-body code {
  background: #161b22;
}

/* Mermaid diagrams */
#preview .mermaid {
  display: flex;
  justify-content: center;
  margin: 16px 0;
  background: transparent;
}

/* KaTeX */
#preview .katex-display {
  overflow-x: auto;
  overflow-y: hidden;
  padding: 4px 0;
}

/* Math error fallback */
#preview .math-error {
  color: #cf222e;
  font-family: var(--font-editor);
}

/* ── Status bar ──────────────────────────────────────────────────────────────── */

#statusbar {
  display: flex;
  align-items: center;
  gap: 6px;
  height: var(--status-h);
  padding: 0 14px;
  background: var(--bg-toolbar);
  border-top: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 11.5px;
  flex-shrink: 0;
}

.stat-sep { opacity: 0.4; }

#stat-mode {
  font-size: 11px;
  opacity: 0.6;
}

/* ── Scrollbars ──────────────────────────────────────────────────────────────── */

#preview-pane::-webkit-scrollbar { width: 7px; }
#preview-pane::-webkit-scrollbar-track { background: transparent; }
#preview-pane::-webkit-scrollbar-thumb {
  background: var(--border);
  border-radius: 4px;
}

/* ── Light theme CM tweaks ───────────────────────────────────────────────────── */

[data-theme="light"] .cm-editor {
  background: #ffffff;
}

[data-theme="light"] .cm-gutters {
  background: #f6f8fa;
  border-right: 1px solid var(--border);
  color: var(--text-muted);
}

[data-theme="light"] .cm-activeLineGutter,
[data-theme="light"] .cm-activeLine {
  background: #f0f3f6;
}

/* ── Responsive: stack on narrow screens ─────────────────────────────────────── */

@media (max-width: 680px) {
  #panes { flex-direction: column; }
  #divider { width: 100%; height: var(--divider-w); cursor: row-resize; }
  #editor-pane, #preview-pane { flex: 1; }
}