:root {
  --bg: #ccc;
  --bg-light: #f2f0e7ff /* #eee */;
  --text: #000;
  --muted: #333;
  --border: #666;
  --mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  --sans: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
}

* { box-sizing: border-box; }

html, body {
  height: 100%;
}

body {
  margin: 0;
  font-family: var(--sans);
  background: var(--bg);
  color: var(--text);
  display: flex;
  flex-direction: column;
}

a { color: inherit; }

.topbar {
  flex: 0 0 auto;
  height: 44px;
  display: flex;
  align-items: center;
  padding: 0 10px;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
}

.nav {
  display: flex;
  align-items: center;
  gap: 8px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  height: 28px;
  padding: 0 10px;
  font-size: 12px;
  text-decoration: none;
  border: 1px solid var(--border);
  border-radius: 6px;
}

.btn.disabled {
  opacity: 0.45;
  pointer-events: none;
}

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

.pane {
  flex: 1 1 50%;
  min-width: 0;
  min-height: 0;
}

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

iframe {
  width: 100%;
  height: 100%;
  border: 0;
  background: white;
}

.pane.right {
  overflow: auto;
  display: flex;
  justify-content: center;
  align-items: center;
  background: var(--bg-light);
  font-size: 16px;
}

.pane.right .highlight {
  overflow: auto;
  background: transparent;
}

.pane.right .highlight pre {
  margin: 0;
  padding: 12px;
  font-family: var(--mono);
  font-size: 16px;
  line-height: 1.45;
  white-space: pre;
  tab-size: 4;
  display: inline-block;
}