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

.topbar {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 14px;
  border-bottom: 1px solid #ddd;
  background: #fafafa;
  flex: 0 0 auto;
}

.topbar .title {
  font-weight: 600;
  font-size: 15px;
}

.topbar .subtitle {
  color: #777;
  font-size: 13px;
}

.topbar .spacer {
  flex: 1;
}

.topbar .url-size {
  color: #777;
  font-size: 12px;
  font-variant-numeric: tabular-nums;
}

.topbar button {
  font-size: 13px;
  padding: 4px 12px;
  border: 1px solid #ccc;
  border-radius: 5px;
  background: #fff;
  cursor: pointer;
}

.topbar button:hover {
  background: #f0f0f0;
}

.topbar button.primary {
  background: #2563eb;
  border-color: #2563eb;
  color: #fff;
}

.topbar button.primary:hover {
  background: #1d4ed8;
}

.panes {
  display: flex;
  flex: 1;
  min-height: 0;
}

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

.pane-preview {
  flex: 1;
  overflow-y: auto;
}

.splitter {
  flex: 0 0 6px;
  cursor: col-resize;
  background: #eee;
  border-left: 1px solid #ddd;
  border-right: 1px solid #ddd;
}

.splitter:hover {
  background: #d5e3fb;
}

.editor-container {
  height: 100%;
  overflow: hidden;
}

.editor-container .cm-editor {
  height: 100%;
}

/* --- rendered markdown --- */

.preview {
  padding: 18px 28px 60px;
  max-width: 820px;
  font-size: 15px;
  line-height: 1.6;
}

.preview h1,
.preview h2,
.preview h3,
.preview h4 {
  line-height: 1.25;
  margin-top: 1.4em;
  margin-bottom: 0.5em;
}

.preview h1:first-child {
  margin-top: 0.3em;
}

.preview h1 {
  font-size: 1.7em;
  border-bottom: 1px solid #eee;
  padding-bottom: 0.2em;
}

.preview h2 {
  font-size: 1.35em;
  border-bottom: 1px solid #f0f0f0;
  padding-bottom: 0.15em;
}

.preview h3 {
  font-size: 1.15em;
}

.preview a {
  color: #2563eb;
}

.preview blockquote {
  margin: 0.8em 0;
  padding: 0.1em 1em;
  border-left: 4px solid #ddd;
  color: #555;
}

.preview code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.9em;
  background: #f3f3f3;
  border-radius: 4px;
  padding: 0.1em 0.35em;
}

.preview pre {
  background: #f8f8f8;
  border: 1px solid #eee;
  border-radius: 6px;
  padding: 12px 14px;
  overflow-x: auto;
  line-height: 1.45;
}

.preview pre code {
  background: none;
  padding: 0;
  font-size: 0.87em;
}

.code-block {
  position: relative;
}

.code-block .copy-button {
  position: absolute;
  top: 6px;
  right: 6px;
  font-size: 11px;
  padding: 2px 8px;
  border: 1px solid #ddd;
  border-radius: 4px;
  background: #fff;
  color: #666;
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.15s;
}

.code-block:hover .copy-button {
  opacity: 1;
}

.code-block .copy-button:hover {
  background: #f0f0f0;
}

.preview table {
  border-collapse: collapse;
  margin: 0.8em 0;
  display: block;
  overflow-x: auto;
}

.preview th,
.preview td {
  border: 1px solid #ddd;
  padding: 5px 12px;
}

.preview th {
  background: #f7f7f7;
}

.preview tr:nth-child(2n) {
  background: #fbfbfb;
}

.preview img {
  max-width: 100%;
}

.preview hr {
  border: none;
  border-top: 1px solid #ddd;
  margin: 1.5em 0;
}

.preview .katex-display {
  overflow-x: auto;
  overflow-y: hidden;
  padding: 2px 0;
}

.preview input[type='checkbox'] {
  margin-right: 0.45em;
}

.mermaid-diagram {
  margin: 0.8em 0;
  overflow-x: auto;
}

.mermaid-loading {
  color: #999;
  font-size: 13px;
  margin: 0.8em 0;
}

.mermaid-error {
  color: #b91c1c;
  background: #fef2f2;
  border: 1px solid #fecaca;
  white-space: pre-wrap;
}