:root {
  --theme-color: #237b57;
  --font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", sans-serif;
  --font-weight: 400;
  --line-height: 1.8;
  --content-max-width: 880px;
}

.markdown-section iframe,
.markdown-section embed,
.markdown-section img {
  max-width: 100%;
}

.markdown-section iframe[src*="youtube.com"] {
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
}

/* Keep SVG coordinates and dimensions intact; scroll wide examples on phones. */
.svg-demo {
  overflow-x: auto;
  margin-block: 1rem;
}

.svg-demo > svg {
  display: block;
  max-width: none;
}

@media (max-width: 640px) {
  :root {
    --content-margin-inline: 20px;
  }
}