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

:root {
  --bg: #f5f6f8;
  --bg2: #ffffff;
  --bg3: #e9ecef;
  --fg: #212529;
  --fg2: #6c757d;
  --accent: #4A90D9;
  --accent-hover: #3a7bc8;
  --border: #dee2e6;
  --success: #28a745;
  --error: #dc3545;
  --radius: 8px;
  --font: 'Segoe UI', system-ui, -apple-system, sans-serif;
  --mono: 'Cascadia Code', 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
}

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

/* Toolbar */
.toolbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 16px;
  background: var(--bg2);
  border-bottom: 1px solid var(--border);
  -webkit-app-region: drag;
  user-select: none;
}

.toolbar-left {
  display: flex;
  align-items: center;
  gap: 10px;
}

.logo {
  font-weight: 700;
  font-size: 15px;
  color: var(--accent);
  letter-spacing: 0.5px;
}

.sep {
  color: var(--border);
}

.subtitle {
  color: var(--fg2);
  font-size: 13px;
}

.toolbar-right {
  display: flex;
  gap: 6px;
  -webkit-app-region: no-drag;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  font-size: 13px;
  font-family: var(--font);
  cursor: pointer;
  transition: all 0.15s;
  -webkit-app-region: no-drag;
}

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

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

.btn-primary:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.btn-secondary {
  background: var(--bg3);
  color: var(--fg);
}

.btn-secondary:hover {
  background: var(--border);
}

/* Container */
.container {
  display: flex;
  height: calc(100vh - 45px);
  overflow: hidden;
}

.panel {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  min-width: 0;
}

.panel-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 6px 14px;
  background: var(--bg2);
  border-bottom: 1px solid var(--border);
  font-size: 12px;
  color: var(--fg2);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  user-select: none;
}

.char-count, .status {
  font-size: 11px;
  color: var(--fg2);
  text-transform: none;
  letter-spacing: 0;
}

.status {
  color: var(--success);
}

/* Resizer */
.resizer {
  width: 4px;
  cursor: col-resize;
  background: var(--border);
  transition: background 0.15s;
  flex-shrink: 0;
}

.resizer:hover {
  background: var(--accent);
}

/* Editor */
textarea#editor {
  flex: 1;
  width: 100%;
  padding: 16px;
  border: none;
  outline: none;
  resize: none;
  font-family: var(--mono);
  font-size: 14px;
  line-height: 1.6;
  background: var(--bg);
  color: var(--fg);
  tab-size: 4;
}

textarea#editor::placeholder {
  color: var(--fg2);
  opacity: 0.5;
}

textarea#editor:focus {
  background: var(--bg);
}

/* Scrollbar styling */
textarea#editor::-webkit-scrollbar,
.preview::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}

textarea#editor::-webkit-scrollbar-track,
.preview::-webkit-scrollbar-track {
  background: #e9ecef;
}

textarea#editor::-webkit-scrollbar-thumb,
.preview::-webkit-scrollbar-thumb {
  background: #adb5bd;
  border-radius: 4px;
}

textarea#editor::-webkit-scrollbar-thumb:hover,
.preview::-webkit-scrollbar-thumb:hover {
  background: #6c757d;
}

/* Preview */
.preview {
  flex: 1;
  padding: 20px;
  overflow-y: auto;
  line-height: 1.6;
  background: white;
  color: #1a1a2e;
}

.preview .placeholder {
  color: #aaa;
  text-align: center;
  padding: 60px 20px;
  font-style: italic;
}

/* Preview typography */
.preview h1 { font-size: 26px; margin: 0 0 16px 0; padding-bottom: 8px; border-bottom: 2px solid var(--border); color: var(--fg); font-weight: 700; }
.preview h2 { font-size: 20px; margin: 24px 0 12px 0; padding-bottom: 6px; border-bottom: 1px solid var(--border); color: var(--fg); font-weight: 600; }
.preview h3 { font-size: 17px; margin: 20px 0 8px 0; color: var(--fg); font-weight: 600; }
.preview h4 { font-size: 15px; margin: 16px 0 6px 0; color: var(--fg); font-weight: 600; }
.preview h5, .preview h6 { font-size: 14px; margin: 12px 0 6px 0; color: var(--fg); font-weight: 600; }
.preview p { margin: 0 0 10px 0; }
.preview strong { font-weight: 700; }
.preview em { font-style: italic; }
.preview code {
  font-family: var(--mono);
  font-size: 13px;
  background: #f0f1f3;
  padding: 2px 6px;
  border-radius: 3px;
  color: #d63384;
}
.preview pre {
  margin: 12px 0;
  background: #f0f1f3;
  border-radius: 6px;
  padding: 14px 16px;
  overflow-x: auto;
  border: 1px solid var(--border);
}
.preview pre code {
  background: none;
  padding: 0;
  color: var(--fg);
  font-size: 13px;
  line-height: 1.5;
}
.preview a { color: var(--accent); text-decoration: none; }
.preview a:hover { text-decoration: underline; }
.preview blockquote {
  margin: 12px 0;
  padding: 8px 16px;
  border-left: 4px solid var(--accent);
  background: #f0f1f3;
  color: var(--fg2);
}
.preview blockquote p { margin: 0; }
.preview ul, .preview ol { margin: 8px 0 8px 24px; }
.preview li { margin: 4px 0; }
.preview table {
  border-collapse: collapse;
  margin: 12px 0;
  width: 100%;
  font-size: 13px;
}
.preview th, .preview td {
  border: 1px solid var(--border);
  padding: 8px 12px;
  text-align: left;
}
.preview th {
  background: var(--bg3);
  font-weight: 600;
}
.preview tr:nth-child(even) { background: #f8f9fa; }
.preview hr { border: none; border-top: 2px solid var(--border); margin: 20px 0; }
.preview img { max-width: 100%; border-radius: 4px; }
.preview del { text-decoration: line-through; color: var(--fg2); }

/* Toast */
.toast {
  position: fixed;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(80px);
  background: var(--bg2);
  color: var(--fg);
  padding: 10px 24px;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  font-size: 13px;
  opacity: 0;
  transition: all 0.3s;
  pointer-events: none;
  z-index: 100;
}

.toast.show {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}