/* TechHub Pro v4.0 — 主样式表 */
:root {
  --accent: #00d4ff;
  --accent2: #7c3aed;
  --accent3: #07c160;
  --bg: #0a0e1a;
  --bg2: #111827;
  --bg3: #1a2236;
  --card: #131c2f;
  --card-hover: #1a2540;
  --text: #e8edf5;
  --text2: #9ca8bd;
  --text3: #5e6b80;
  --border: rgba(255,255,255,0.08);
  --shadow: 0 8px 30px rgba(0,0,0,0.4);
  --radius: 14px;
  --success: #07c160;
  --warn: #f59e0b;
  --danger: #ef4444;
  --grad: linear-gradient(135deg, var(--accent), var(--accent2));
  --grad2: linear-gradient(135deg, #ff6b6b, #ffd93d, #6bcb77, #4d96ff);
}

[data-theme="light"] {
  --bg: #f5f7fb;
  --bg2: #ffffff;
  --bg3: #eef1f7;
  --card: #ffffff;
  --card-hover: #f0f4fa;
  --text: #1a1f2e;
  --text2: #4a5568;
  --text3: #718096;
  --border: rgba(0,0,0,0.08);
  --shadow: 0 4px 20px rgba(0,0,0,0.08);
}

* { margin:0; padding:0; box-sizing:border-box; }
html { scroll-behavior:smooth; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg); color: var(--text);
  line-height:1.6; overflow-x:hidden;
  transition: background .3s, color .3s;
}

a { color: var(--accent); text-decoration: none; }
a:hover { filter: brightness(1.15); }
img { max-width:100%; display:block; }
button { font: inherit; cursor: pointer; border: none; background: none; color: inherit; }

/* ===== 滚动进度条 ===== */
.scroll-progress {
  position: fixed; top:0; left:0; height:3px; width:0%;
  background: var(--grad); z-index:9999;
  transition: width .15s ease-out;
}

/* ===== 导航栏 ===== */
.navbar {
  position: fixed; top:0; left:0; right:0; z-index:1000;
  backdrop-filter: blur(14px);
  background: rgba(10,14,26,0.75);
  border-bottom: 1px solid var(--border);
  transition: background .3s, box-shadow .3s;
}
.navbar.scrolled { box-shadow: var(--shadow); }
.nav-inner {
  max-width:1280px; margin:0 auto;
  display:flex; align-items:center; gap:24px;
  padding:12px 24px;
}
.brand { display:flex; align-items:center; gap:8px; font-weight:700; font-size:1.1rem; }
.brand-logo { font-size:1.4rem; }
.brand-name em { color: var(--accent); font-style:normal; }
.nav { display:flex; gap:6px; flex:1; }
.nav a {
  padding:8px 14px; border-radius:8px; color:var(--text2);
  font-size:0.92rem; transition: all .2s;
}
.nav a:hover, .nav a.active {
  color: var(--text); background: var(--bg3);
}
.nav-actions { display:flex; align-items:center; gap:10px; }
.icon-btn {
  width:38px; height:38px; border-radius:8px;
  display:inline-flex; align-items:center; justify-content:center;
  font-size:1.2rem; background:var(--bg3); transition:all .2s;
}
.icon-btn:hover { background: var(--accent); color:#fff; }
.btn-contact {
  padding:8px 14px; border-radius:8px; background:var(--grad);
  color:#fff; font-size:0.88rem; font-weight:600;
}
.hamburger { display:none; font-size:1.4rem; }

/* ===== Hero ===== */
.hero {
  position:relative; min-height:100vh;
  display:flex; align-items:center; justify-content:center;
  padding:100px 24px 60px; overflow:hidden;
  background:
    radial-gradient(ellipse 80% 60% at 50% 0%, rgba(0,212,255,0.12), transparent),
    radial-gradient(ellipse 60% 50% at 80% 50%, rgba(124,58,237,0.1), transparent),
    var(--bg);
}
#particles-canvas { position:absolute; inset:0; width:100%; height:100%; z-index:0; }
.hero-inner { position:relative; z-index:1; text-align:center; max-width:900px; }
.hero-badge {
  display:inline-block; padding:6px 16px; border-radius:20px;
  background:rgba(7,193,96,0.15); color:var(--accent3);
  font-size:0.85rem; font-weight:600; margin-bottom:24px;
  border:1px solid rgba(7,193,96,0.3);
}
.hero-title {
  font-size: clamp(2rem, 5vw, 3.6rem); font-weight:800; line-height:1.2;
  margin-bottom:20px;
}
.hero-title .grad {
  background: var(--grad); -webkit-background-clip:text; -webkit-text-fill-color:transparent;
  background-clip:text;
}
.hero-title em { color:var(--accent2); font-style:normal; }
.hero-sub { font-size:1.15rem; color:var(--text2); margin-bottom:36px; }
.hero-stats {
  display:flex; gap:40px; justify-content:center; margin-bottom:36px;
  flex-wrap:wrap;
}
.hero-stats > div { text-align:center; }
.hero-stats b { display:block; font-size:2rem; font-weight:800; color:var(--accent); }
.hero-stats span { font-size:0.88rem; color:var(--text2); }
.hero-cta { display:flex; gap:16px; justify-content:center; flex-wrap:wrap; }
.btn-primary {
  padding:14px 32px; border-radius:10px; font-weight:700; font-size:1rem;
  background:var(--grad); color:#fff; transition:all .25s;
  box-shadow: 0 4px 20px rgba(0,212,255,0.3);
}
.btn-primary:hover { transform:translateY(-2px); box-shadow:0 6px 30px rgba(0,212,255,0.5); }
.btn-ghost {
  padding:14px 28px; border-radius:10px; font-weight:600;
  border:2px solid var(--border); color:var(--text);
  transition:all .2s;
}
.btn-ghost:hover { border-color:var(--accent); color:var(--accent); }

.hero-floats { position:absolute; inset:0; pointer-events:none; z-index:1; }
.float-card {
  position:absolute; padding:10px 18px; border-radius:10px;
  background:var(--card); border:1px solid var(--border);
  font-size:0.85rem; font-weight:600; color:var(--text2);
  animation:float 6s ease-in-out infinite;
}
.fc1 { top:20%; left:8%; animation-delay:0s; }
.fc2 { top:55%; right:10%; animation-delay:2s; }
.fc3 { bottom:15%; left:15%; animation-delay:4s; }
@keyframes float {
  0%,100% { transform:translateY(0); }
  50% { transform:translateY(-12px); }
}

/* ===== 鼠标光晕 ===== */
.mouse-glow {
  position:absolute; width:400px; height:400px; border-radius:50%;
  background:radial-gradient(circle, rgba(0,212,255,0.08), transparent 70%);
  pointer-events:none; opacity:0; transition:opacity .4s;
  z-index:0; will-change:transform;
}

/* ===== Section ===== */
.section { padding:80px 24px; max-width:1280px; margin:0 auto; }
.section.alt { background:var(--bg2); border-radius:24px; margin:40px auto; }
.section-head {
  display:flex; align-items:center; justify-content:space-between;
  margin-bottom:36px; flex-wrap:wrap; gap:12px;
}
.section-head h2 { font-size:1.8rem; font-weight:800; }
.section-head h2::before { content:" "; }
.more { font-size:0.9rem; color:var(--accent); font-weight:600; }
.result-count { color:var(--text3); font-size:0.9rem; }

/* ===== 筛选栏 ===== */
.filter-bar {
  display:flex; gap:16px; flex-wrap:wrap; align-items:center;
  margin-bottom:28px; padding:16px;
  background:var(--bg2); border-radius:12px; border:1px solid var(--border);
}
.filter-group { display:flex; gap:8px; flex-wrap:wrap; }
.chip {
  padding:6px 14px; border-radius:20px; font-size:0.85rem;
  background:var(--bg3); color:var(--text2); transition:all .2s;
  border:1px solid transparent;
}
.chip:hover { color:var(--text); }
.chip.active { background:var(--accent); color:#fff; font-weight:600; }
.filter-search { display:flex; gap:10px; margin-left:auto; flex-wrap:wrap; }
.filter-search input {
  padding:8px 16px; border-radius:8px; border:1px solid var(--border);
  background:var(--bg3); color:var(--text); font-size:0.9rem; min-width:240px;
}
.filter-search input:focus { outline:none; border-color:var(--accent); }
.filter-search select {
  padding:8px 12px; border-radius:8px; border:1px solid var(--border);
  background:var(--bg3); color:var(--text); font-size:0.9rem;
}

/* ===== 课程网格 ===== */
.courses-grid {
  display:grid; grid-template-columns:repeat(auto-fill, minmax(290px, 1fr));
  gap:20px;
}
.empty-tip {
  grid-column:1/-1; text-align:center; padding:60px;
  color:var(--text3); font-size:1.1rem;
}
.loading { grid-column:1/-1; text-align:center; padding:40px; color:var(--text3); }

.course-card {
  background:var(--card); border-radius:var(--radius);
  border:1px solid var(--border); overflow:hidden;
  transition:all .3s; display:flex; flex-direction:column;
}
.course-card:hover {
  transform:translateY(-4px); border-color:var(--accent);
  box-shadow:var(--shadow);
}
.card-cover {
  height:100px; display:flex; align-items:flex-start; justify-content:space-between;
  padding:14px; position:relative; overflow:hidden;
}
.card-cover::after {
  content:""; position:absolute; inset:0;
  background:linear-gradient(180deg, transparent 40%, rgba(0,0,0,0.35));
}
.card-cat {
  font-size:0.78rem; font-weight:700; color:#fff;
  background:rgba(0,0,0,0.35); padding:3px 10px; border-radius:10px;
  z-index:1;
}
.badge { z-index:1; font-size:0.78rem; font-weight:700; padding:3px 10px; border-radius:10px; }
.badge-free { background:rgba(7,193,96,0.9); color:#fff; }
.badge-price { background:rgba(245,158,11,0.9); color:#fff; }
.card-body { padding:18px; flex:1; display:flex; flex-direction:column; }
.card-body h3 { font-size:1rem; font-weight:700; margin-bottom:8px; line-height:1.4; }
.card-desc { font-size:0.85rem; color:var(--text2); flex:1; margin-bottom:12px; }
.card-meta { display:flex; gap:12px; font-size:0.78rem; color:var(--text3); margin-bottom:14px; flex-wrap:wrap; }
.card-actions { display:flex; gap:10px; }
.card-actions button { padding:9px 16px; border-radius:8px; font-size:0.88rem; font-weight:600; flex:1; transition:all .2s; }
.btn-free { background:var(--success); color:#fff; }
.btn-free:hover { filter:brightness(1.1); }
.btn-buy { background:var(--grad); color:#fff; }
.btn-buy:hover { filter:brightness(1.15); transform:scale(1.02); }
.btn-paid { background:rgba(7,193,96,0.15); color:var(--success); border:1px solid var(--success); }
.btn-detail { background:var(--bg3) !important; color:var(--text2) !important; flex:0 0 auto !important; padding:9px 14px !important; }

/* ===== B站 ===== */
.bilibili-grid {
  display:grid; grid-template-columns:repeat(auto-fill, minmax(280px, 1fr)); gap:16px;
}
.bili-card {
  display:block; background:var(--card); border-radius:var(--radius);
  border:1px solid var(--border); overflow:hidden; transition:all .3s;
}
.bili-card:hover { transform:translateY(-3px); border-color:var(--accent); }
.bili-cover {
  height:90px; display:flex; align-items:center; justify-content:center;
  background:linear-gradient(135deg, #fb7299, #fc9b7a); color:#fff;
  font-size:2rem; font-weight:800;
}
.bili-body { padding:14px; }
.bili-body h4 { font-size:0.95rem; margin-bottom:8px; line-height:1.4; }
.bili-meta { display:flex; gap:12px; font-size:0.78rem; color:var(--text3); flex-wrap:wrap; }

/* ===== GitHub ===== */
.github-grid {
  display:grid; grid-template-columns:repeat(auto-fill, minmax(300px, 1fr)); gap:16px;
}
.gh-card {
  display:block; background:var(--card); border-radius:var(--radius);
  border:1px solid var(--border); padding:18px; transition:all .3s;
}
.gh-card:hover { transform:translateY(-3px); border-color:var(--accent2); }
.gh-header { display:flex; justify-content:space-between; align-items:center; margin-bottom:8px; }
.gh-name { font-weight:700; font-size:0.95rem; }
.gh-lang { font-size:0.78rem; color:var(--text3); }
.gh-card p { font-size:0.85rem; color:var(--text2); margin-bottom:10px; }
.gh-meta { display:flex; gap:14px; font-size:0.8rem; color:var(--text3); }
.gh-cat {
  margin-left:auto; padding:2px 8px; border-radius:6px;
  background:var(--bg3); font-size:0.75rem;
}

/* ===== 资源 ===== */
.resources-grid {
  display:grid; grid-template-columns:repeat(auto-fill, minmax(260px, 1fr)); gap:14px;
}
.res-card {
  display:block; background:var(--card); border-radius:var(--radius);
  border:1px solid var(--border); padding:16px; transition:all .3s;
  position:relative; overflow:hidden;
}
.res-card:hover { transform:translateY(-2px); border-color:var(--accent); }
.res-card h4 { font-size:0.95rem; margin-bottom:6px; }
.res-card p { font-size:0.82rem; color:var(--text2); }
.res-tag {
  display:inline-block; margin-top:10px; padding:3px 10px; border-radius:8px;
  font-size:0.75rem; font-weight:600;
}
.tag-must { background:rgba(239,68,68,0.15); color:var(--danger); }
.tag-free { background:rgba(7,193,96,0.15); color:var(--success); }
.tag-pro { background:rgba(245,158,11,0.15); color:var(--warn); }

/* ===== 排行 ===== */
.rankings-grid {
  display:grid; grid-template-columns:repeat(auto-fill, minmax(340px, 1fr)); gap:16px;
}
.rank-card {
  background:var(--card); border-radius:var(--radius);
  border:1px solid var(--border); padding:18px; transition:all .3s;
}
.rank-card:hover { border-color:var(--accent); }
.rank-head { display:flex; align-items:center; gap:12px; margin-bottom:10px; }
.rank-no { font-size:1.4rem; font-weight:900; color:var(--accent); }
.rank-name { font-weight:700; flex:1; }
.rank-score { font-weight:800; color:var(--accent2); }
.rank-link { font-size:1.2rem; opacity:0.6; }
.rank-link:hover { opacity:1; }
.rank-bar { height:6px; background:var(--bg3); border-radius:3px; overflow:hidden; margin-bottom:8px; }
.rank-bar > div { height:100%; background:var(--grad); border-radius:3px; transition:width 1s ease; }
.rank-card p { font-size:0.85rem; color:var(--text2); }

/* ===== 路线 ===== */
.paths-grid {
  display:grid; grid-template-columns:repeat(auto-fill, minmax(300px, 1fr)); gap:16px;
}
.path-card {
  background:var(--card); border-radius:var(--radius);
  border:1px solid var(--border); padding:20px; transition:all .3s;
}
.path-card:hover { transform:translateY(-3px); border-color:var(--accent2); }
.path-card h4 { font-size:1.05rem; margin-bottom:6px; }
.path-dur { font-size:0.82rem; color:var(--text3); }
.path-card ol { margin:12px 0 12px 20px; font-size:0.88rem; color:var(--text2); }
.path-card ol li { margin-bottom:4px; }
.path-link { font-size:0.85rem; font-weight:600; }

/* ===== 支付说明 ===== */
.pay-info-grid {
  display:grid; grid-template-columns:repeat(auto-fill, minmax(300px, 1fr)); gap:16px;
}
.pay-info-card {
  background:var(--card); border-radius:var(--radius);
  border:1px solid var(--border); padding:20px;
}
.pay-info-card h3 { font-size:1.05rem; margin-bottom:12px; color:var(--accent); }
.pay-info-card ol { margin-left:20px; font-size:0.88rem; color:var(--text2); }
.pay-info-card ol li { margin-bottom:6px; }
.pay-info-card p { font-size:0.88rem; color:var(--text2); margin-bottom:6px; }

/* ===== 页脚 ===== */
.footer {
  background:var(--bg2); border-top:1px solid var(--border);
  padding:48px 24px 24px; margin-top:60px;
}
.footer-inner {
  max-width:1280px; margin:0 auto;
  display:flex; gap:48px; flex-wrap:wrap; justify-content:space-between;
}
.footer-brand { display:flex; gap:14px; align-items:flex-start; }
.footer-brand .brand-logo { font-size:2rem; }
.footer-brand b { font-size:1.1rem; }
.footer-brand p { font-size:0.82rem; color:var(--text3); margin-top:4px; }
.footer-links { display:flex; gap:48px; flex-wrap:wrap; }
.footer-links h4 { font-size:0.85rem; color:var(--text3); margin-bottom:10px; text-transform:uppercase; letter-spacing:1px; }
.footer-links a { display:block; font-size:0.88rem; color:var(--text2); margin-bottom:6px; }
.footer-links a:hover { color:var(--accent); }
.footer-bottom {
  max-width:1280px; margin:32px auto 0; padding-top:20px;
  border-top:1px solid var(--border);
  display:flex; justify-content:space-between; flex-wrap:wrap; gap:10px;
  font-size:0.8rem; color:var(--text3);
}

/* ===== 入场动画 ===== */
.reveal { opacity:0; transform:translateY(30px); transition:all .6s ease; }
.reveal.revealed { opacity:1; transform:translateY(0); }

/* ===== Toast ===== */
.toast {
  position:fixed; bottom:30px; left:50%; transform:translateX(-50%) translateY(20px);
  padding:12px 24px; border-radius:10px; font-size:0.92rem; font-weight:600;
  z-index:9999; opacity:0; transition:all .3s; pointer-events:none;
}
.toast.show { opacity:1; transform:translateX(-50%) translateY(0); }
.toast-success { background:#07c160; color:#fff; }
.toast-error { background:#ef4444; color:#fff; }
.toast-info { background:#3b82f6; color:#fff; }

/* ===== 响应式 ===== */
@media (max-width:900px) {
  .nav { display:none; }
  .hamburger { display:inline-flex; align-items:center; justify-content:center; }
  .hero-stats { gap:24px; }
  .filter-bar { flex-direction:column; align-items:stretch; }
  .filter-search { margin-left:0; }
  .footer-inner { flex-direction:column; }
}
@media (max-width:600px) {
  .hero-title { font-size:1.8rem; }
  .hero-stats b { font-size:1.5rem; }
  .section { padding:50px 16px; }
  .float-card { display:none; }
}