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

:root {
  --bg: #ffffff;
  --surface: #f5f5f5;
  --border: #e0e0e0;
  --text: #1a1a1a;
  --text-secondary: #666666;
  --editor-bg: #fafafa;
  --header-bg: #f0f0f0;
  --accent: #4a9eff;
  --error: #e74c3c;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1e1e2e;
    --surface: #282840;
    --border: #3a3a5c;
    --text: #e0e0e0;
    --text-secondary: #a0a0b0;
    --editor-bg: #22223a;
    --header-bg: #2a2a44;
    --accent: #89b4fa;
    --error: #f38ba8;
  }
}

html, body {
  height: 100%;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
}

.container {
  display: grid;
  grid-template-columns: 1fr 6px 1fr;
  height: 100vh;
  overflow: hidden;
}

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

.pane-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 16px;
  background: var(--header-bg);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.zoom-controls {
  display: flex;
  align-items: center;
  gap: 6px;
}

.zoom-controls button {
  background: var(--surface);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 4px;
  padding: 2px 8px;
  font-size: 13px;
  cursor: pointer;
  line-height: 1.4;
}

.zoom-controls button:hover {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

#zoom-level {
  font-size: 12px;
  font-variant-numeric: tabular-nums;
  color: var(--text-secondary);
  min-width: 3.5em;
  text-align: center;
}

.pane-title {
  font-size: 12px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-secondary);
}

#editor {
  flex: 1;
  width: 100%;
  padding: 16px;
  background: var(--editor-bg);
  color: var(--text);
  border: none;
  outline: none;
  resize: none;
  font-family: "SF Mono", "Fira Code", "JetBrains Mono", Menlo, Monaco, "Courier New", monospace;
  font-size: 14px;
  line-height: 1.6;
  tab-size: 2;
}

#editor::placeholder {
  color: var(--text-secondary);
  opacity: 0.6;
}

.divider {
  background: var(--border);
  cursor: col-resize;
  transition: background 0.15s;
}

.divider:hover, .divider.dragging {
  background: var(--accent);
}

#preview {
  flex: 1;
  overflow: auto;
  padding: 24px;
  display: flex;
  align-items: flex-start;
  justify-content: center;
}

#preview svg {
  height: auto;
  transform-origin: center top;
}

#preview .error {
  color: var(--error);
  font-family: "SF Mono", Menlo, monospace;
  font-size: 13px;
  white-space: pre-wrap;
  padding: 16px;
  background: var(--surface);
  border-radius: 8px;
  border: 1px solid var(--error);
  width: 100%;
}

#preview .placeholder {
  color: var(--text-secondary);
  font-size: 14px;
  text-align: center;
  padding-top: 40px;
}

/* Responsive: stack vertically on narrow screens */
@media (max-width: 700px) {
  .container {
    grid-template-columns: 1fr;
    grid-template-rows: 1fr 6px 1fr;
  }

  .divider {
    cursor: row-resize;
  }
}