:root {
  --bg: #f5f6f8;
  --bg-card: #ffffff;
  --bg-sidebar: #ffffff;
  --bg-header: #ffffff;
  --text: #1f2329;
  --text-sub: #8a8f99;
  --text-faint: #b6bbc4;
  --border: #ececf0;
  --primary: #3a86ff;
  --primary-soft: #eaf2ff;
  --hover: #f2f4f7;
  --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 4px 16px rgba(0,0,0,0.04);
  --shadow-hover: 0 6px 24px rgba(58,134,255,0.16);
  --radius: 12px;
  --header-h: 60px;
  --sidebar-w: 150px;
}

html[data-theme="dark"] {
  --bg: #14161a;
  --bg-card: #1c1f26;
  --bg-sidebar: #1a1d23;
  --bg-header: #1a1d23;
  --text: #e6e8ec;
  --text-sub: #8a8f99;
  --text-faint: #5a5f6b;
  --border: #2a2e37;
  --primary: #4f93ff;
  --primary-soft: #1f2a3d;
  --hover: #23272f;
  --shadow: 0 1px 3px rgba(0,0,0,0.4);
  --shadow-hover: 0 6px 24px rgba(0,0,0,0.5);
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

a { text-decoration: none; color: inherit; }

/* ---------- 顶部导航 ---------- */
.header {
  position: sticky; top: 0; z-index: 100;
  height: var(--header-h);
  background: var(--bg-header);
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(8px);
}

.header-inner {
  max-width: 1400px; margin: 0 auto;
  height: 100%; padding: 0 20px;
  display: flex; align-items: center; gap: 18px;
}

.logo {
  display: flex; align-items: center; gap: 8px; flex-shrink: 0;
}

.logo-mark {
  width: 32px; height: 32px; border-radius: 8px;
  background: linear-gradient(135deg, #3a86ff, #5f5fff);
  color: #fff; font-weight: 800; font-size: 18px;
  display: grid; place-items: center;
  box-shadow: 0 4px 12px rgba(58,134,255,0.35);
}

.logo-text {
  font-size: 18px; font-weight: 700;
}

.logo-text i {
  font-style: normal; font-weight: 400;
  color: var(--text-sub); font-size: 14px; margin-left: 2px;
}

.search-box {
  flex: 1; max-width: 560px; display: flex; align-items: center;
  background: var(--bg); border: 1.5px solid var(--border);
  border-radius: 999px; overflow: hidden;
  transition: border-color 0.2s, box-shadow 0.2s;
}

.search-box:focus-within {
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-soft);
}

.search-engine {
  border: none; background: transparent; color: var(--text-sub);
  padding: 0 10px; height: 38px; font-size: 13px;
  cursor: pointer; outline: none;
}

.search-input {
  flex: 1; border: none; background: transparent;
  height: 38px; padding: 0 8px; font-size: 14px;
  color: var(--text); outline: none;
}

.search-btn {
  border: none; background: var(--primary); color: #fff;
  height: 38px; padding: 0 18px; font-size: 13px;
  cursor: pointer; border-radius: 999px; margin: 0 3px;
  transition: filter 0.2s;
}

.search-btn:hover { filter: brightness(1.08); }

.header-actions { display: flex; gap: 6px; flex-shrink: 0; }

.icon-btn {
  width: 36px; height: 36px; border: 1px solid var(--border);
  border-radius: 8px; background: var(--bg); color: var(--text-sub);
  display: grid; place-items: center; cursor: pointer;
  font-size: 16px; transition: all 0.2s;
}

.icon-btn:hover { color: var(--primary); border-color: var(--primary); }

/* ---------- 顶部下拉导航 ---------- */
.top-nav {
  position: sticky; top: var(--header-h); z-index: 99;
  background: var(--bg-header); border-bottom: 1px solid var(--border);
}

.top-nav-inner {
  max-width: 1400px; margin: 0 auto; padding: 0 20px;
  display: flex; align-items: center; gap: 2px;
  overflow-x: auto; scrollbar-width: none;
}

.top-nav-inner::-webkit-scrollbar { display: none; }

.nav-group { position: relative; }

.nav-trigger {
  display: flex; align-items: center; gap: 3px;
  border: none; background: transparent; color: var(--text-sub);
  font-size: 13px; font-weight: 500; padding: 10px 12px;
  cursor: pointer; transition: color 0.18s;
}

.nav-group:hover .nav-trigger,
.nav-group.open .nav-trigger { color: var(--primary); }

.nav-caret {
  font-size: 9px; transition: transform 0.18s;
}

.nav-group:hover .nav-caret,
.nav-group.open .nav-caret { transform: rotate(180deg); }

.nav-dropdown {
  position: absolute; top: 100%; left: 0; min-width: 140px;
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: 10px; box-shadow: var(--shadow); padding: 6px;
  opacity: 0; visibility: hidden; transform: translateY(6px);
  transition: opacity 0.18s, transform 0.18s, visibility 0.18s;
}

.nav-group:hover .nav-dropdown,
.nav-group.open .nav-dropdown {
  opacity: 1; visibility: visible; transform: translateY(0);
}

.nav-dropdown a {
  display: block; padding: 7px 11px; border-radius: 6px;
  font-size: 13px; color: var(--text-sub); white-space: nowrap;
  transition: all 0.15s;
}

.nav-dropdown a:hover { background: var(--hover); color: var(--primary); }

/* ---------- 布局 ---------- */
.layout {
  max-width: 1400px; margin: 0 auto;
  display: flex; gap: 20px; padding: 20px;
  align-items: flex-start;
}

/* ---------- 侧边栏 ---------- */
.sidebar {
  position: sticky; top: calc(var(--header-h) + 48px);
  width: var(--sidebar-w); flex-shrink: 0;
  background: var(--bg-sidebar); border-radius: var(--radius);
  box-shadow: var(--shadow); padding: 8px;
  max-height: calc(100vh - var(--header-h) - 68px);
  overflow-y: auto;
}

.side-nav a {
  display: flex; align-items: center; gap: 8px;
  padding: 9px 10px; border-radius: 8px;
  color: var(--text-sub); font-size: 13px; font-weight: 500;
  transition: all 0.18s; cursor: pointer;
}

.side-nav a:hover { background: var(--hover); color: var(--text); }

.side-nav a.active {
  background: var(--primary-soft); color: var(--primary); font-weight: 600;
}

.side-nav a .nav-icon { font-size: 15px; width: 18px; text-align: center; }

/* ---------- 主内容 ---------- */
.main { flex: 1; min-width: 0; }

.hero {
  background: linear-gradient(135deg, #3a86ff, #6a5cff);
  color: #fff; border-radius: 16px; padding: 32px 28px;
  margin-bottom: 24px;
  box-shadow: 0 10px 30px rgba(58,134,255,0.25);
}

.hero h1 { font-size: 24px; margin-bottom: 6px; }

.hero p { opacity: 0.9; font-size: 14px; }

/* 分类区块 */
.category {
  margin-bottom: 32px;
  scroll-margin-top: calc(var(--header-h) + 50px);
}

.category-title {
  display: flex; align-items: center; gap: 8px;
  font-size: 17px; font-weight: 700; margin-bottom: 14px;
  padding-bottom: 10px; border-bottom: 2px solid var(--border);
}

.category-title .cat-icon { font-size: 18px; }

.category-title .cat-count {
  font-size: 12px; font-weight: 400;
  color: var(--text-faint); margin-left: 4px;
}

/* 卡片网格 */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(210px, 1fr));
  gap: 12px;
}

.card {
  background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 14px;
  display: flex; gap: 10px; align-items: flex-start;
  box-shadow: var(--shadow);
  transition: transform 0.18s, box-shadow 0.18s, border-color 0.18s;
  cursor: pointer;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-hover);
  border-color: var(--primary);
}

.card-icon {
  width: 38px; height: 38px; border-radius: 9px;
  flex-shrink: 0; display: grid; place-items: center;
  font-size: 16px; font-weight: 700; color: #fff;
}

.card-body { min-width: 0; flex: 1; }

.card-name {
  font-size: 14px; font-weight: 600;
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}

.card-desc {
  font-size: 12px; color: var(--text-sub); margin-top: 3px;
  display: -webkit-box; -webkit-line-clamp: 2;
  -webkit-box-orient: vertical; overflow: hidden;
}

.card-meta {
  display: flex; align-items: center; gap: 6px; margin-top: 5px;
}

.card-views {
  font-size: 11px; color: var(--text-faint);
  display: flex; align-items: center; gap: 2px;
}

.card-tag {
  font-size: 10px; color: var(--primary);
  background: var(--primary-soft);
  padding: 1px 6px; border-radius: 4px;
}

/* 空状态 */
.empty {
  text-align: center; padding: 80px 20px; color: var(--text-sub);
}

.empty .emoji {
  font-size: 48px; display: block; margin-bottom: 12px;
}

/* ---------- 页脚 ---------- */
.footer {
  margin-top: 36px; padding: 24px 0;
  border-top: 1px solid var(--border);
  text-align: center; color: var(--text-sub); font-size: 13px;
}

.footer a { color: var(--primary); }

/* ICP备案 */
.footer-icp { margin-top: 6px; font-size: 12px; }

.footer-icp a {
  color: var(--text-faint); transition: color 0.2s;
}

.footer-icp a:hover { color: var(--primary); }

/* ---------- 返回顶部 ---------- */
.back-top {
  position: fixed; right: 24px; bottom: 24px;
  width: 44px; height: 44px; border-radius: 50%;
  border: none; background: var(--primary); color: #fff;
  font-size: 18px; cursor: pointer;
  box-shadow: 0 6px 20px rgba(58,134,255,0.4);
  opacity: 0; visibility: hidden; transform: translateY(10px);
  transition: all 0.25s; z-index: 90;
}

.back-top.show {
  opacity: 1; visibility: visible; transform: translateY(0);
}

/* ---------- 响应式 ---------- */
/* 平板：缩小侧边栏 */
@media (max-width: 1024px) {
  :root { --sidebar-w: 120px; }
  .layout { gap: 14px; padding: 14px; }
  .card-grid { grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); }
  .hero { padding: 24px 20px; }
  .hero h1 { font-size: 20px; }
  .hero p { font-size: 13px; }
}

/* 窄屏：隐藏侧边栏、优化卡片 */
@media (max-width: 768px) {
  :root { --header-h: 52px; }
  .sidebar { display: none; }
  .layout { padding: 10px; }
  .header-inner { gap: 10px; padding: 0 10px; }
  .search-box { max-width: none; }
  .search-engine { padding: 0 6px; font-size: 12px; }
  .search-btn { padding: 0 12px; font-size: 12px; }
  .card-grid { grid-template-columns: repeat(2, 1fr); gap: 8px; }
  .card { padding: 10px; gap: 8px; }
  .card-icon { width: 32px; height: 32px; font-size: 14px; border-radius: 7px; }
  .card-name { font-size: 13px; }
  .card-desc { font-size: 11px; }
  .hero { padding: 20px 16px; margin-bottom: 16px; }
  .hero h1 { font-size: 18px; }
  .hero p { font-size: 12px; }
  .back-top { right: 14px; bottom: 14px; width: 40px; height: 40px; }
  .logo-text { font-size: 15px; }
  .logo-text i { display: none; }
}

/* 手机：双列卡片 */
@media (max-width: 480px) {
  .card-grid { grid-template-columns: repeat(2, 1fr); gap: 6px; }
  .card { flex-direction: column; padding: 10px; gap: 6px; }
  .card-icon { width: 28px; height: 28px; font-size: 13px; }
  .category { margin-bottom: 22px; }
  .category-title { font-size: 15px; margin-bottom: 10px; }
}

/* 滚动条美化 */
.sidebar::-webkit-scrollbar { width: 4px; }
.sidebar::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }