:root {
  --bg: #ffffff;
  --bg-soft: #f6f8fa;
  --bg-side: #fafbfc;
  --text: #1f2328;
  --text-soft: #57606a;
  --border: #d8dee4;
  --link: #0074ff;         /* Vela 官方蓝 */
  --accent: #0074ff;       /* Vela 官方蓝 */
  --accent-soft: #eaf3ff;
  --code-bg: #f6f8fa;
  --sidebar-w: 300px;
  --header-h: 56px;
  --shadow: 0 1px 3px rgba(0,0,0,.08);
}
[data-theme="dark"] {
  --bg: #0d1117;
  --bg-soft: #161b22;
  --bg-side: #0d1117;
  --text: #e6edf3;
  --text-soft: #8b949e;
  --border: #30363d;
  --link: #58a6ff;
  --accent: #4098ff;       /* Vela 官方蓝（深色加强） */
  --accent-soft: #0c2236;
  --code-bg: #161b22;
  --shadow: 0 1px 3px rgba(0,0,0,.4);
}
* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  font-size: 15px;
}
a { color: var(--link); text-decoration: none; }
a:hover { text-decoration: underline; }

/* 顶栏 */
.header {
  position: fixed; top: 0; left: 0; right: 0; height: var(--header-h);
  display: flex; align-items: center; gap: 16px;
  padding: 0 18px;
  background: var(--bg); border-bottom: 1px solid var(--border);
  z-index: 50;
}
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; white-space: nowrap; }
.brand .logo-img {
  width: 30px; height: 30px; border-radius: 6px;
  display: block;
}
.brand small { color: var(--text-soft); font-weight: 500; font-size: 12px; }
.search {
  flex: 1; max-width: 460px; position: relative;
}
.search input {
  width: 100%; height: 36px; padding: 0 12px 0 34px;
  border: 1px solid var(--border); border-radius: 8px;
  background: var(--bg-soft); color: var(--text); font-size: 14px;
}
.search input:focus { outline: none; border-color: var(--accent); }
.search svg { position: absolute; left: 10px; top: 9px; opacity: .5; }
.search-results {
  position: absolute; top: 42px; left: 0; right: 0;
  background: var(--bg); border: 1px solid var(--border); border-radius: 8px;
  box-shadow: var(--shadow); max-height: 360px; overflow: auto; display: none; z-index: 60;
}
.search-results.show { display: block; }
.search-results .sr-item { padding: 9px 12px; border-bottom: 1px solid var(--border); cursor: pointer; }
.search-results .sr-item:hover { background: var(--bg-soft); }
.search-results .sr-item .sec { font-size: 11px; color: var(--text-soft); }
.search-results .sr-item .tt { font-weight: 600; }
.search-results .sr-item .ex { font-size: 12px; color: var(--text-soft); }
.menu-btn {
  border: 1px solid var(--border); background: var(--bg-soft); color: var(--text);
  width: 36px; height: 36px; border-radius: 8px; cursor: pointer; font-size: 16px;
  display: flex; align-items: center; justify-content: center;
}
.menu-btn { display: none; }

/* 移动端侧边栏遮罩层 */
.sidebar-overlay {
  display: none;
  position: fixed; left: 0; right: 0; top: var(--header-h); bottom: 0;
  background: rgba(0,0,0,.42); z-index: 35;
}

/* 布局 */
.layout { display: flex; padding-top: var(--header-h); }
.sidebar {
  width: var(--sidebar-w); flex: 0 0 var(--sidebar-w);
  height: calc(100vh - var(--header-h)); position: sticky; top: var(--header-h);
  overflow-y: auto; background: var(--bg-side);
  border-right: 1px solid var(--border); padding: 14px 10px 40px;
}
.main { flex: 1; min-width: 0; }
.content {
  max-width: 920px; margin: 0 auto; padding: 30px 36px 80px;
}

/* 侧边栏导航 */
.nav-section { margin-bottom: 14px; }
.nav-section > .sec-title {
  font-size: 12px; font-weight: 800; letter-spacing: .04em; text-transform: uppercase;
  color: var(--text-soft); padding: 6px 10px; display: flex; align-items: center; gap: 6px;
}
.nav-section > .sec-title .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--accent); }
.nav-group > .group-label {
  display: flex; align-items: center; gap: 6px; padding: 6px 10px;
  cursor: pointer; border-radius: 6px; color: var(--text); font-weight: 600; font-size: 14px;
}
.nav-group > .group-label:hover { background: var(--bg-soft); }
.nav-group > .group-label .arrow { margin-left: auto; transition: transform .15s; opacity: .5; font-size: 11px; }
.nav-group.collapsed > .group-label .arrow { transform: rotate(-90deg); }
.nav-group.collapsed > .group-children { display: none; }
.nav-group.single > .group-label .arrow { display: none; }
.nav-link {
  display: block; padding: 5px 10px 5px 22px; border-radius: 6px;
  color: var(--text-soft); font-size: 13.5px; cursor: pointer;
}
.nav-link:hover { background: var(--bg-soft); color: var(--text); text-decoration: none; }
.nav-link.active { background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.nav-group.leaf > .group-label.active { background: var(--accent-soft); color: var(--accent); }
.group-children .group-children { padding-left: 8px; border-left: 1px dashed var(--border); margin-left: 10px; }

/* 顶层可折叠大标题（Vela 教学 / JavaScript 教学） */
.nav-topgroup {
  margin-bottom: 12px; border: 1px solid var(--border); border-radius: 10px; overflow: hidden;
  background: var(--bg);
}
.nav-topgroup > .group-label.top-label {
  font-size: 15px; font-weight: 800; color: var(--accent);
  padding: 12px 12px; background: var(--accent-soft); letter-spacing: .02em;
}
.nav-topgroup > .group-label.top-label .arrow { opacity: .65; }
.nav-topgroup > .group-children { padding: 4px 4px 8px; }
.nav-topgroup > .group-children .sec-label {
  font-size: 13.5px; font-weight: 700; color: var(--text);
  padding: 8px 10px; border-radius: 6px; margin-top: 2px;
}
.nav-topgroup > .group-children .sec-label:hover { background: var(--bg-soft); }

/* 内容区 */
.teach-callout {
  background: var(--accent-soft); border: 1px solid color-mix(in srgb, var(--accent) 35%, transparent);
  border-radius: 10px; padding: 12px 16px; margin-bottom: 22px; font-size: 13.5px; color: var(--text);
}
.teach-callout b { color: var(--accent); }
.content h1 { font-size: 28px; margin: 0 0 18px; padding-bottom: 10px; border-bottom: 1px solid var(--border); }
.content h2 { font-size: 21px; margin: 30px 0 12px; padding-bottom: 6px; border-bottom: 1px solid var(--border); }
.content h3 { font-size: 17px; margin: 22px 0 10px; }
.content p { margin: 12px 0; }
.content ul, .content ol { padding-left: 24px; }
.content li { margin: 5px 0; }
.content code {
  background: var(--code-bg); padding: .15em .4em; border-radius: 5px;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace; font-size: 13px;
}
.content pre {
  background: var(--code-bg); border: 1px solid var(--border); border-radius: 10px;
  padding: 14px 16px; overflow: auto; margin: 14px 0;
}
.content pre code { background: none; padding: 0; }
.content table { border-collapse: collapse; width: 100%; margin: 14px 0; font-size: 13.5px; }
.content th, .content td { border: 1px solid var(--border); padding: 8px 10px; text-align: left; }
.content th { background: var(--bg-soft); }
.content blockquote {
  border-left: 4px solid var(--accent); margin: 14px 0; padding: 4px 16px;
  background: var(--bg-soft); color: var(--text-soft); border-radius: 0 8px 8px 0;
}
.content img { max-width: 100%; height: auto; border-radius: 8px; }

/* 编程示例卡片网格 */
.samples-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: 18px; margin: 20px 0 8px;
}
.sample-card {
  border: 1px solid var(--border); border-radius: 12px; background: var(--bg);
  overflow: hidden; display: flex; flex-direction: column; box-shadow: var(--shadow);
  transition: transform .15s, border-color .15s;
}
.sample-card:hover { transform: translateY(-3px); border-color: var(--accent); }
.sample-cover {
  width: 100%; height: 180px; object-fit: contain; padding: 12px;
  background: var(--bg-soft); border-bottom: 1px solid var(--border);
}
.sample-body { padding: 14px 16px 16px; display: flex; flex-direction: column; flex: 1; }
.sample-name { font-size: 16px; margin: 0 0 6px; }
.sample-desc { font-size: 13px; color: var(--text-soft); margin: 0 0 14px; flex: 1; }
.sample-links { display: flex; flex-wrap: wrap; gap: 8px; }
.repo-link {
  font-size: 12.5px; padding: 4px 12px; border-radius: 999px;
  border: 1px solid var(--border); color: var(--text); font-weight: 600;
}
.repo-link:hover {
  text-decoration: none; border-color: var(--accent);
  color: var(--accent); background: var(--accent-soft);
}

/* 上下页 */
.pager { display: flex; justify-content: space-between; gap: 12px; margin-top: 44px; border-top: 1px solid var(--border); padding-top: 18px; }
.pager a { flex: 1; padding: 12px 14px; border: 1px solid var(--border); border-radius: 10px; background: var(--bg-soft); }
.pager a:hover { border-color: var(--accent); text-decoration: none; }
.pager .plabel { font-size: 12px; color: var(--text-soft); }
.pager .ptitle { font-weight: 600; color: var(--text); }
.pager .next { text-align: right; }

footer.foot { text-align: center; color: var(--text-soft); font-size: 12px; padding: 24px; border-top: 1px solid var(--border); }

/* 响应式 */
@media (max-width: 860px) {
  .sidebar {
    position: fixed; left: 0; top: var(--header-h); bottom: 0; z-index: 40;
    transform: translateX(-100%); transition: transform .2s; width: 80vw; max-width: 320px;
  }
  .sidebar.open { transform: translateX(0); }
  .sidebar-overlay.show { display: block; }
  .menu-btn { display: flex; }
  .content { padding: 22px 18px 70px; }
  .brand small { display: none; }
  .brand { font-size: 14px; }
  .brand span { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; min-width: 0; }

  /* 移动端搜索：默认收成图标胶囊，点击展开为顶部悬浮胶囊 */
  .header { gap: 10px; padding: 0 12px; }
  .search {
    flex: 0 0 auto; width: 40px; height: 40px; margin-left: auto;
    display: flex; align-items: center; justify-content: center;
    background: var(--bg-soft); border: 1px solid var(--border); border-radius: 999px;
    cursor: pointer; overflow: visible;
  }
  .search input { display: none; }
  .search svg { position: static; opacity: .65; }
  .search-results { display: none; }
  .search.expanded {
    position: fixed; top: calc(var(--header-h) + 12px); left: 50%; transform: translateX(-50%);
    width: calc(100% - 40px); height: auto; margin: 0; z-index: 70;
    display: flex; align-items: center; gap: 10px;
    background: var(--bg); border: 1.5px solid var(--accent); border-radius: 999px;
    box-shadow: 0 12px 36px rgba(0,0,0,.25); padding: 7px 16px;
  }
  .search.expanded input {
    display: block; flex: 1; width: 100%; border: none; background: transparent;
    height: 34px; padding: 0; font-size: 16px; color: var(--text);
  }
  .search.expanded input:focus { outline: none; }
  .search.expanded svg { position: static; opacity: .65; flex: 0 0 auto; }
  .search.expanded .search-results {
    position: fixed; top: calc(var(--header-h) + 66px); left: 50%; transform: translateX(-50%);
    width: calc(100% - 40px); border-radius: 14px; z-index: 70;
    box-shadow: 0 12px 36px rgba(0,0,0,.25);
    max-height: calc(100vh - 150px);
  }
}