/* ============================================================
   青少年 AI 素养专区 · youth.css
   XT-YOUTH-20260916 · 仅本页使用，复用 cg-unified.css 变量
   CSP 约束：style-src 'self' → 本文件为唯一内联替代，页面零 <style>、零 style="" 属性
   移动端优先：单列布局 · 大按钮 · 正文 ≥16px
   ============================================================ */

/* ---------- Hero ---------- */
.yt-hero {
  position: relative;
  padding: 46px 20px 40px;
  color: #fff;
  background: linear-gradient(160deg, #0B1220 0%, #12203F 46%, #1E3A8A 100%);
  overflow: hidden;
}
.yt-hero::after {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(460px 240px at 12% 0%, rgba(37, 99, 235, .40), transparent 72%),
    radial-gradient(400px 240px at 92% 18%, rgba(6, 182, 212, .30), transparent 72%);
  pointer-events: none;
}
.yt-hero-inner {
  position: relative;
  z-index: 1;
  max-width: 880px;
  margin: 0 auto;
  text-align: center;
}
.yt-hero h1 {
  margin: 16px 0 14px;
  font-size: clamp(28px, 7.2vw, 46px);
  font-weight: 800;
  line-height: 1.22;
  letter-spacing: -.5px;
}
.yt-hero-sub {
  max-width: 660px;
  margin: 0 auto;
  font-size: 16px;
  line-height: 1.75;
  color: rgba(255, 255, 255, .84);
}

/* 路径导航条：启蒙 → 动手 → 进阶 */
.yt-flow {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 8px;
  margin-top: 24px;
}
.yt-flow-step {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 8px 15px;
  font-size: 15px;
  font-weight: 600;
  color: #fff;
  border-radius: 999px;
  background: rgba(255, 255, 255, .12);
  border: 1px solid rgba(255, 255, 255, .20);
}
.yt-flow-arrow {
  font-size: 15px;
  color: rgba(255, 255, 255, .55);
}

/* ---------- 三站学习路径 ---------- */
.yt-path {
  display: grid;
  grid-template-columns: 1fr;
  gap: 18px;
  margin-top: 6px;
}
.yt-station {
  display: flex;
  flex-direction: column;
  padding: 26px 22px 22px;
  background: var(--cg-white, #fff);
  border: 1px solid var(--border-color, #E2E8F0);
  border-radius: 18px;
  box-shadow: 0 6px 24px rgba(15, 23, 42, .06);
  transition: transform .2s ease, box-shadow .2s ease, border-color .2s ease;
}
.yt-station:hover {
  transform: translateY(-4px);
  border-color: var(--cg-slate-300, #CBD5E1);
  box-shadow: 0 16px 38px rgba(15, 23, 42, .13);
}
.yt-station-badge {
  align-self: flex-start;
  margin-bottom: 16px;
  padding: 5px 12px;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: .5px;
  color: var(--cg-primary, #2563EB);
  background: var(--cg-primary-50, #EFF6FF);
  border-radius: 999px;
}
.yt-station-icon {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 64px;
  height: 64px;
  margin-bottom: 16px;
  color: #fff;
  border-radius: 16px;
}
.yt-station-icon svg { width: 34px; height: 34px; }
.yt-icon-1 { background: linear-gradient(135deg, #2563EB, #06B6D4); }
.yt-icon-2 { background: linear-gradient(135deg, #7C3AED, #EC4899); }
.yt-icon-3 { background: linear-gradient(135deg, #F59E0B, #EF4444); }
.yt-station h3 {
  margin: 0 0 8px;
  font-size: 20px;
  color: var(--text-primary, #0F172A);
}
.yt-station-tag {
  flex: 1;
  margin: 0 0 16px;
  font-size: 16px;
  line-height: 1.7;
  color: var(--text-secondary, #475569);
}
.yt-age {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  margin-bottom: 18px;
  font-size: 16px;
  color: var(--text-muted, #64748B);
}
.yt-age svg { width: 17px; height: 17px; flex: none; }
.yt-station .cg-btn {
  justify-content: center;
  width: 100%;
  font-size: 17px;
}

/* ---------- 家长必读 ---------- */
.yt-surface { background: var(--bg-surface, #F8FAFC); }
.yt-faq-list {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
}
.yt-faq-item {
  padding: 18px 20px;
  background: #fff;
  border: 1px solid var(--border-color, #E2E8F0);
  border-radius: 14px;
}
.yt-faq-item h3 {
  margin: 0 0 8px;
  font-size: 17px;
  color: var(--text-primary, #0F172A);
}
.yt-faq-item p {
  margin: 0;
  font-size: 16px;
  line-height: 1.75;
  color: var(--text-secondary, #475569);
}

/* ---------- 桌面端 ---------- */
@media (min-width: 720px) {
  .yt-hero { padding: 72px 32px 60px; }
  .yt-path { grid-template-columns: repeat(3, 1fr); }
  .yt-faq-list { grid-template-columns: repeat(2, 1fr); }
}