/* ===== AI Awing 学习站样式 ===== */
:root {
  --bg: #070a13;
  --bg-soft: #0c1120;
  --card: #111731;
  --border: rgba(148, 163, 184, .14);
  --text: #e6e9f2;
  --text-dim: #98a2b8;
  --primary: #6366f1;
  --primary-2: #a855f7;
  --radius: 16px;
  --maxw: 1160px;
}
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
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: 1.65;
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration: none; }
.container { max-width: var(--maxw); margin: 0 auto; padding: 0 24px; }
.container-narrow { max-width: 820px; }
.grad {
  background: linear-gradient(92deg, var(--primary), var(--primary-2));
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  padding: 10px 22px; border-radius: 999px; font-size: 15px; font-weight: 600;
  transition: transform .18s ease, box-shadow .18s ease, background .18s ease;
  white-space: nowrap;
}
.btn-primary {
  background: linear-gradient(92deg, var(--primary), var(--primary-2));
  color: #fff; box-shadow: 0 8px 26px rgba(99, 102, 241, .35);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 12px 32px rgba(99, 102, 241, .5); }
.btn-ghost {
  border: 1px solid var(--border); color: var(--text);
  background: rgba(148, 163, 184, .06);
}
.btn-ghost:hover { border-color: rgba(148, 163, 184, .4); background: rgba(148, 163, 184, .12); }
.btn-lg { padding: 14px 34px; font-size: 16px; }
.btn-block { width: 100%; }

/* ===== 导航 ===== */
.nav {
  position: sticky; top: 0; z-index: 50;
  backdrop-filter: blur(14px); -webkit-backdrop-filter: blur(14px);
  background: rgba(7, 10, 19, .78);
  border-bottom: 1px solid var(--border);
}
.nav-inner { display: flex; align-items: center; justify-content: space-between; height: 64px; }
.brand { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 18px; }
.brand-mark { display: inline-flex; }
.nav-links { display: flex; gap: 28px; font-size: 15px; color: var(--text-dim); }
.nav-links a { transition: color .15s; }
.nav-links a:hover, .nav-links a.active { color: var(--text); }
.nav-toggle {
  display: none; flex-direction: column; gap: 5px; background: none; border: 0; cursor: pointer; padding: 6px;
}
.nav-toggle span { width: 22px; height: 2px; background: var(--text); border-radius: 2px; transition: .25s; }
.nav-links.open { display: flex; flex-direction: column; position: absolute; top: 64px; left: 0; right: 0; background: var(--bg-soft); border-bottom: 1px solid var(--border); padding: 18px 24px; gap: 16px; }

/* ===== Hero ===== */
.hero { position: relative; overflow: hidden; padding: 84px 0 60px; text-align: center; }
.hero-glow {
  position: absolute; inset: -40% -20% auto; height: 90%;
  background:
    radial-gradient(600px 320px at 28% 30%, rgba(99, 102, 241, .28), transparent 60%),
    radial-gradient(600px 320px at 72% 34%, rgba(168, 85, 247, .22), transparent 60%);
  pointer-events: none;
}
.hero-inner { position: relative; }
.hero-badge {
  display: inline-flex; align-items: center; gap: 8px;
  border: 1px solid var(--border); border-radius: 999px;
  padding: 6px 16px; font-size: 13px; color: var(--text-dim);
  background: rgba(148, 163, 184, .05);
}
.hero-badge .dot { width: 8px; height: 8px; border-radius: 50%; background: #34d399; box-shadow: 0 0 8px #34d399; }
.hero-title { font-size: clamp(40px, 7vw, 68px); line-height: 1.15; font-weight: 800; margin: 26px 0 18px; letter-spacing: -1px; }
.hero-sub { max-width: 640px; margin: 0 auto 32px; font-size: 17.5px; color: var(--text-dim); }
.hero-actions { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }

/* 首页搜索 */
.hero-search {
  max-width: 560px; margin: 34px auto 0; display: flex; align-items: center; gap: 8px;
  background: var(--card); border: 1px solid var(--border); border-radius: 999px;
  padding: 8px 8px 8px 20px; color: var(--text-dim); transition: border-color .2s;
}
.hero-search:focus-within { border-color: rgba(99, 102, 241, .6); }
.hero-search input {
  flex: 1; background: none; border: 0; outline: none; color: var(--text);
  font-size: 15px; font-family: inherit;
}
.hero-search input::placeholder { color: rgba(148, 163, 184, .6); }
.hero-search button {
  border: 0; background: linear-gradient(92deg, var(--primary), var(--primary-2)); color: #fff;
  font-size: 14px; font-weight: 600; padding: 9px 22px; border-radius: 999px; cursor: pointer;
  transition: transform .15s;
}
.hero-search button:hover { transform: scale(1.03); }

.hero-stats {
  display: flex; justify-content: center; gap: 56px; margin: 44px 0 0; flex-wrap: wrap;
}
.hero-stats div { display: flex; flex-direction: column; gap: 2px; }
.hero-stats strong { font-size: 30px; font-weight: 800; }
.hero-stats span { font-size: 13px; color: var(--text-dim); }

/* ===== 通用区块 ===== */
.section { padding: 92px 0; }
.section-alt { background: var(--bg-soft); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.section-head { text-align: center; max-width: 680px; margin: 0 auto 56px; }
.section-tag {
  display: inline-block; font-size: 13px; font-weight: 600; letter-spacing: 1px;
  color: var(--primary); border: 1px solid rgba(99, 102, 241, .35);
  padding: 4px 14px; border-radius: 999px; margin-bottom: 16px;
  background: rgba(99, 102, 241, .08);
}
.section-head h2 { font-size: clamp(28px, 4vw, 40px); font-weight: 800; letter-spacing: -.5px; margin-bottom: 14px; }
.section-head p { color: var(--text-dim); font-size: 16px; }

/* 三步学习法 */
.steps { display: grid; grid-template-columns: 1fr auto 1fr auto 1fr; gap: 18px; align-items: center; }
.step { text-align: center; padding: 30px 22px; }
.step-num {
  width: 52px; height: 52px; margin: 0 auto 16px; border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 17px; font-weight: 800; color: #fff;
  background: linear-gradient(135deg, var(--primary), var(--primary-2));
  box-shadow: 0 8px 24px rgba(99, 102, 241, .35);
}
.step h3 { font-size: 18px; margin-bottom: 10px; }
.step p { font-size: 14.5px; color: var(--text-dim); }
.step-arrow { font-size: 24px; color: rgba(148, 163, 184, .4); }

/* 学习路线 */
.roadmap { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }
.roadmap-card {
  position: relative; background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 30px 26px; display: flex; flex-direction: column;
  transition: transform .2s, border-color .2s;
}
.roadmap-card:hover { transform: translateY(-4px); border-color: rgba(99, 102, 241, .45); }
.roadmap-top { display: flex; justify-content: space-between; align-items: center; margin-bottom: 16px; }
.roadmap-phase {
  font-size: 13px; font-weight: 700; padding: 4px 14px; border-radius: 999px;
  background: linear-gradient(92deg, var(--primary), var(--primary-2)); color: #fff;
}
.roadmap-time { font-size: 12.5px; color: var(--text-dim); }
.roadmap-card h3 { font-size: 19px; margin-bottom: 14px; }
.roadmap-card ul { list-style: none; flex: 1; }
.roadmap-card li { padding: 7px 0 7px 22px; position: relative; font-size: 14.5px; color: var(--text-dim); }
.roadmap-card li::before { content: "✓"; position: absolute; left: 0; color: var(--primary); font-weight: 700; }
.roadmap-out {
  margin-top: 18px; padding: 12px 14px; border-radius: 10px; font-size: 13.5px;
  background: rgba(99, 102, 241, .1); border: 1px solid rgba(99, 102, 241, .25);
  color: var(--text);
}

/* 知识体系卡片 */
.cards { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.card {
  display: block; background: var(--card); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 26px 24px; transition: transform .2s, border-color .2s;
}
.card:hover { transform: translateY(-4px); border-color: rgba(99, 102, 241, .45); }
.card-ico {
  width: 46px; height: 46px; border-radius: 12px; display: flex; align-items: center; justify-content: center;
  margin-bottom: 16px; color: var(--c, var(--primary));
  background: color-mix(in srgb, var(--c, var(--primary)) 14%, transparent);
  border: 1px solid color-mix(in srgb, var(--c, var(--primary)) 28%, transparent);
}
.card-head { display: flex; align-items: baseline; justify-content: space-between; margin-bottom: 8px; }
.card-head h3 { font-size: 17px; }
.card-count { font-size: 12.5px; color: var(--text-dim); white-space: nowrap; }
.card p { font-size: 14px; color: var(--text-dim); line-height: 1.6; }

/* 精选手册 */
.handbooks { display: grid; grid-template-columns: 1fr 1fr; gap: 22px; }
.handbook-card {
  display: flex; gap: 20px; background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 30px 28px; align-items: flex-start;
  transition: transform .2s, border-color .2s;
}
.handbook-card:hover { transform: translateY(-4px); border-color: rgba(99, 102, 241, .45); }
.handbook-icon { font-size: 38px; line-height: 1; }
.handbook-body h3 { font-size: 19px; margin-bottom: 10px; }
.handbook-desc { font-size: 14px; color: var(--text-dim); margin-bottom: 14px; }
.handbook-meta { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.kb-tag {
  font-size: 11.5px; padding: 3px 10px; border-radius: 999px;
  background: rgba(99, 102, 241, .12); color: #a5b4fc; border: 1px solid rgba(99, 102, 241, .25);
}
.kb-tag.size { background: rgba(148, 163, 184, .1); color: var(--text-dim); border-color: var(--border); }
.handbook-cta { margin-left: auto; font-size: 13.5px; font-weight: 600; color: #a5b4fc; }

/* 推荐课程 */
.courses { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.course-card {
  display: flex; gap: 16px; align-items: flex-start; background: var(--card);
  border: 1px solid var(--border); border-radius: var(--radius); padding: 22px 20px;
  transition: transform .2s, border-color .2s;
}
.course-card:hover { transform: translateY(-4px); border-color: rgba(99, 102, 241, .45); }
.course-avatar {
  width: 44px; height: 44px; border-radius: 12px; flex-shrink: 0;
  display: flex; align-items: center; justify-content: center;
  font-size: 17px; font-weight: 700; color: #fff;
  background: linear-gradient(135deg, color-mix(in srgb, var(--c) 80%, #fff 0%), var(--c));
}
.course-body h3 { font-size: 15.5px; margin-bottom: 6px; }
.course-body p { font-size: 13.5px; color: var(--text-dim); margin-bottom: 8px; }
.course-meta { font-size: 12px; color: #a5b4fc; }

/* CTA */
.cta { padding: 96px 0; text-align: center; position: relative; overflow: hidden; }
.cta::before {
  content: ""; position: absolute; inset: 0;
  background: radial-gradient(700px 260px at 50% 50%, rgba(99, 102, 241, .22), transparent 65%);
}
.cta-inner { position: relative; }
.cta h2 { font-size: clamp(28px, 4.5vw, 44px); font-weight: 800; margin-bottom: 14px; letter-spacing: -.5px; }
.cta p { color: var(--text-dim); font-size: 17px; margin-bottom: 30px; }
.cta-note { display: block; margin-top: 18px; font-size: 13px; color: var(--text-dim); }

/* 页脚 */
.footer { border-top: 1px solid var(--border); padding: 64px 0 28px; background: var(--bg-soft); }
.footer-inner { display: flex; justify-content: space-between; gap: 40px; flex-wrap: wrap; padding-bottom: 40px; }
.footer-brand { max-width: 320px; }
.footer-brand .brand-name { font-size: 18px; font-weight: 700; }
.footer-brand p { font-size: 14px; color: var(--text-dim); margin-top: 10px; }
.footer-cols { display: flex; gap: 64px; flex-wrap: wrap; }
.footer-col { display: flex; flex-direction: column; gap: 10px; }
.footer-col h4 { font-size: 14px; margin-bottom: 6px; }
.footer-col a { font-size: 14px; color: var(--text-dim); transition: color .15s; }
.footer-col a:hover { color: var(--text); }
.footer-bottom {
  display: flex; justify-content: space-between; align-items: center; flex-wrap: wrap; gap: 8px;
  border-top: 1px solid var(--border); padding-top: 22px; font-size: 13px; color: var(--text-dim);
}

/* ===== 响应式 ===== */
@media (max-width: 1080px) {
  .cards { grid-template-columns: repeat(3, 1fr); }
  .courses { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 860px) {
  .cards { grid-template-columns: repeat(2, 1fr); }
  .roadmap { grid-template-columns: 1fr; }
  .handbooks { grid-template-columns: 1fr; }
  .steps { grid-template-columns: 1fr; }
  .step-arrow { transform: rotate(90deg); text-align: center; }
  .hero-stats { gap: 32px; }
}
@media (max-width: 640px) {
  .nav-links { display: none; }
  .nav-toggle { display: flex; }
  .cards, .courses { grid-template-columns: 1fr; }
  .section { padding: 64px 0; }
  .hero { padding: 60px 0 44px; }
  .footer-cols { gap: 36px; }
}