:root {
  --bg-deep: #070b14;
  --bg-panel: #0d1524;
  --bg-card: #0f1828;
  --line-soft: rgba(0, 229, 204, 0.14);
  --line-mid: rgba(0, 229, 204, 0.28);
  --accent: #00e5cc;
  --accent-dim: rgba(0, 229, 204, 0.12);
  --violet: #7c5cff;
  --text-main: #e9f2f2;
  --text-sub: #8fa3b8;
  --text-faint: #56687d;
  --radius-md: 10px;
  --radius-lg: 16px;
  --font-stack: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Segoe UI", sans-serif;
}

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

html { scroll-behavior: smooth; }

body {
  background: var(--bg-deep);
  color: var(--text-main);
  font-family: var(--font-stack);
  font-size: 15px;
  line-height: 1.7;
  min-height: 100vh;
  overflow-x: hidden;
}

a { color: inherit; text-decoration: none; }
button { font-family: var(--font-stack); cursor: pointer; border: none; background: none; color: inherit; }

.bg-grid {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(0, 229, 204, 0.045) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 229, 204, 0.045) 1px, transparent 1px);
  background-size: 44px 44px;
  mask-image: radial-gradient(ellipse 90% 70% at 50% 0%, #000 30%, transparent 75%);
  -webkit-mask-image: radial-gradient(ellipse 90% 70% at 50% 0%, #000 30%, transparent 75%);
}

.bg-glow {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background:
    radial-gradient(ellipse 60% 40% at 15% -5%, rgba(0, 229, 204, 0.10), transparent 60%),
    radial-gradient(ellipse 50% 35% at 85% 10%, rgba(124, 92, 255, 0.08), transparent 60%);
}

.page { position: relative; z-index: 1; }

.wrap { max-width: 1120px; margin: 0 auto; padding: 0 24px; }

/* ---------- 顶部导航 ---------- */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
  padding: 0 28px;
  background: rgba(7, 11, 20, 0.82);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--line-soft);
}

.nav-brand { display: flex; align-items: center; gap: 12px; }

.nav-logo {
  width: 34px;
  height: 34px;
  border-radius: 9px;
  display: grid;
  place-items: center;
  font-size: 17px;
  font-weight: 600;
  color: #04110d;
  background: linear-gradient(135deg, var(--accent), #19b8ff);
  box-shadow: 0 0 18px rgba(0, 229, 204, 0.45);
}

.nav-name { font-size: 17px; font-weight: 600; letter-spacing: 1px; }
.nav-domain { font-size: 12px; color: var(--text-faint); letter-spacing: 0.5px; }

.nav-links { display: flex; gap: 26px; font-size: 14px; color: var(--text-sub); }
.nav-links a { transition: color 0.2s; padding: 6px 2px; }
.nav-links a:hover { color: var(--accent); }

/* ---------- Hero ---------- */
.hero { padding: 88px 0 64px; text-align: center; position: relative; }

.hero-tag {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--accent);
  border: 1px solid var(--line-mid);
  background: var(--accent-dim);
  border-radius: 999px;
  padding: 6px 16px;
  margin-bottom: 26px;
  animation: fade-up 0.7s ease both;
}

.hero-tag .dot {
  width: 7px; height: 7px; border-radius: 50%;
  background: var(--accent);
  animation: pulse 2s infinite;
}

.hero h1 {
  font-size: 46px;
  font-weight: 600;
  line-height: 1.25;
  letter-spacing: 2px;
  margin-bottom: 20px;
  animation: fade-up 0.7s 0.1s ease both;
}

.hero h1 .hl {
  background: linear-gradient(120deg, var(--accent) 20%, #19b8ff 80%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-sub {
  font-size: 16px;
  color: var(--text-sub);
  max-width: 620px;
  margin: 0 auto 36px;
  animation: fade-up 0.7s 0.2s ease both;
}

.hero-cta { display: flex; gap: 16px; justify-content: center; animation: fade-up 0.7s 0.3s ease both; }

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 46px;
  padding: 0 30px;
  border-radius: var(--radius-md);
  font-size: 15px;
  font-weight: 500;
  letter-spacing: 1px;
  transition: transform 0.2s, box-shadow 0.2s, border-color 0.2s;
}

.btn-primary {
  color: #04110d;
  background: linear-gradient(135deg, var(--accent), #19b8ff);
  box-shadow: 0 4px 24px rgba(0, 229, 204, 0.35);
}
.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 8px 32px rgba(0, 229, 204, 0.5); }

.btn-ghost {
  color: var(--text-main);
  border: 1px solid var(--line-mid);
  background: rgba(15, 24, 40, 0.6);
}
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); }

/* ---------- 数据条 ---------- */
.stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-lg);
  overflow: hidden;
  margin: 10px 0 76px;
}

.stat { background: var(--bg-panel); padding: 22px 12px; text-align: center; }
.stat-num { font-size: 26px; font-weight: 600; color: var(--accent); letter-spacing: 1px; }
.stat-label { font-size: 13px; color: var(--text-faint); margin-top: 4px; }

/* ---------- 区块标题 ---------- */
.section { padding: 28px 0 72px; }

.section-head { display: flex; align-items: baseline; justify-content: space-between; margin-bottom: 30px; }
.section-title { font-size: 24px; font-weight: 600; letter-spacing: 1.5px; }
.section-title::before { content: "//"; color: var(--accent); margin-right: 10px; font-weight: 400; }
.section-more { font-size: 13px; color: var(--text-faint); }

/* ---------- 课程卡片 ---------- */
.course-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 22px; }

.course-card {
  position: relative;
  background: var(--bg-card);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-lg);
  padding: 26px 26px 22px;
  transition: transform 0.25s, border-color 0.25s, box-shadow 0.25s;
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.course-card::after {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
  opacity: 0;
  transition: opacity 0.25s;
}

.course-card:hover { transform: translateY(-4px); border-color: var(--line-mid); box-shadow: 0 12px 40px rgba(0, 0, 0, 0.5); }
.course-card:hover::after { opacity: 1; }

.course-badges { display: flex; gap: 8px; margin-bottom: 14px; flex-wrap: wrap; }

.badge {
  font-size: 12px;
  padding: 3px 10px;
  border-radius: 6px;
  letter-spacing: 0.5px;
  border: 1px solid var(--line-mid);
  color: var(--accent);
  background: var(--accent-dim);
}
.badge.violet { color: #b9a6ff; border-color: rgba(124, 92, 255, 0.4); background: rgba(124, 92, 255, 0.12); }
.badge.free { color: #7dda8a; border-color: rgba(125, 218, 138, 0.35); background: rgba(125, 218, 138, 0.1); }

.course-card h3 { font-size: 19px; font-weight: 600; margin-bottom: 8px; letter-spacing: 0.5px; }
.course-card .desc { font-size: 13.5px; color: var(--text-sub); margin-bottom: 16px; flex: 1; }

.course-meta { display: flex; align-items: center; justify-content: space-between; border-top: 1px dashed var(--line-soft); padding-top: 14px; }
.course-price { font-size: 22px; font-weight: 600; color: var(--accent); }
.course-price .unit { font-size: 12px; color: var(--text-faint); font-weight: 400; margin-left: 4px; }
.course-price .origin { font-size: 13px; color: var(--text-faint); text-decoration: line-through; margin-right: 8px; font-weight: 400; }

.btn-small { min-height: 38px; padding: 0 20px; font-size: 13.5px; border-radius: 8px; }

/* ---------- 差异化 ---------- */
.why-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; }

.why-card {
  background: var(--bg-panel);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-lg);
  padding: 26px 24px;
  transition: border-color 0.25s;
}
.why-card:hover { border-color: var(--line-mid); }

.why-icon {
  width: 44px; height: 44px;
  border-radius: 11px;
  display: grid; place-items: center;
  font-size: 20px;
  background: var(--accent-dim);
  border: 1px solid var(--line-mid);
  margin-bottom: 16px;
}

.why-card h4 { font-size: 16px; font-weight: 600; margin-bottom: 8px; }
.why-card p { font-size: 13.5px; color: var(--text-sub); }

/* ---------- 课程详情页 ---------- */
.crumb { display: flex; align-items: center; gap: 8px; font-size: 13px; color: var(--text-faint); padding: 26px 0 0; }
.crumb a:hover { color: var(--accent); }

.course-hero { padding: 26px 0 40px; }
.course-hero h1 { font-size: 32px; font-weight: 600; letter-spacing: 1px; margin: 14px 0 12px; }
.course-hero .lead { font-size: 15px; color: var(--text-sub); max-width: 720px; }

.course-layout { display: grid; grid-template-columns: 1fr 340px; gap: 28px; align-items: start; padding-bottom: 70px; }

.panel {
  background: var(--bg-card);
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-lg);
  padding: 26px;
}

.panel-title { font-size: 18px; font-weight: 600; margin-bottom: 18px; letter-spacing: 1px; }
.panel-title::before { content: "//"; color: var(--accent); margin-right: 8px; font-weight: 400; }

/* 配套学习资源面板（课程详情页） */
.resources-panel { margin-top: 28px; }
.resource-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 14px; }
.resource-item {
  display: flex; gap: 12px; align-items: flex-start;
  background: var(--bg-deep); border: 1px solid var(--line-soft);
  border-radius: var(--radius-md); padding: 14px 16px;
}
.resource-icon { font-size: 20px; line-height: 1.3; }
.resource-name { font-size: 14px; font-weight: 600; color: var(--text-main); margin-bottom: 4px; }
.resource-desc { font-size: 13px; color: var(--text-sub); line-height: 1.6; }

.chapter {
  border: 1px solid var(--line-soft);
  border-radius: var(--radius-md);
  margin-bottom: 12px;
  overflow: hidden;
  background: rgba(13, 21, 36, 0.5);
  transition: border-color 0.2s;
}
.chapter:hover { border-color: var(--line-mid); }

.chapter-head {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 15px 18px;
  text-align: left;
  font-size: 14.5px;
}

.chapter-idx {
  flex: none;
  width: 30px; height: 30px;
  border-radius: 8px;
  display: grid; place-items: center;
  font-size: 13px;
  font-weight: 600;
  color: var(--accent);
  background: var(--accent-dim);
  border: 1px solid var(--line-mid);
}

.chapter-title { flex: 1; font-weight: 500; }
.chapter-state { flex: none; font-size: 12px; padding: 3px 10px; border-radius: 6px; }
.chapter-state.free { color: #7dda8a; background: rgba(125, 218, 138, 0.1); border: 1px solid rgba(125, 218, 138, 0.3); }
.chapter-state.lock { color: var(--text-faint); background: rgba(86, 104, 125, 0.12); border: 1px solid rgba(86, 104, 125, 0.3); }

.chapter-arrow { flex: none; color: var(--text-faint); font-size: 12px; transition: transform 0.25s; }
.chapter.open .chapter-arrow { transform: rotate(90deg); }

.chapter-body { display: none; border-top: 1px dashed var(--line-soft); padding: 16px 18px; font-size: 13.5px; color: var(--text-sub); }
.chapter.open .chapter-body { display: block; }

.chapter-body ul { list-style: none; }
.chapter-body li { padding: 4px 0 4px 18px; position: relative; }
.chapter-body li::before { content: "▸"; position: absolute; left: 0; color: var(--accent); }

.preview-note {
  margin-top: 12px;
  font-size: 12.5px;
  color: #7dda8a;
  background: rgba(125, 218, 138, 0.08);
  border: 1px dashed rgba(125, 218, 138, 0.3);
  border-radius: 8px;
  padding: 8px 12px;
}

/* 购买侧栏 */
.buy-box { position: sticky; top: 84px; }

.buy-price { display: flex; align-items: baseline; gap: 10px; margin-bottom: 4px; }
.buy-price .now { font-size: 34px; font-weight: 600; color: var(--accent); }
.buy-price .origin { font-size: 14px; color: var(--text-faint); text-decoration: line-through; }
.buy-price .off { font-size: 12px; color: #ff9d5c; border: 1px solid rgba(255, 157, 92, 0.4); border-radius: 6px; padding: 2px 8px; }

.buy-sub { font-size: 12.5px; color: var(--text-faint); margin-bottom: 18px; }

.buy-list { list-style: none; margin-bottom: 22px; }
.buy-list li { font-size: 13.5px; color: var(--text-sub); padding: 6px 0 6px 24px; position: relative; }
.buy-list li::before { content: "✓"; position: absolute; left: 0; color: var(--accent); font-weight: 600; }

.btn-block { width: 100%; min-height: 50px; font-size: 16px; }

.buy-safe { margin-top: 14px; font-size: 12px; color: var(--text-faint); text-align: center; }

/* ---------- 弹窗 ---------- */
.modal-mask {
  position: fixed;
  inset: 0;
  z-index: 100;
  background: rgba(3, 6, 12, 0.78);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  display: none;
  align-items: center;
  justify-content: center;
  padding: 20px;
}
.modal-mask.show { display: flex; animation: mask-in 0.2s ease; }

.modal {
  position: relative;
  width: min(440px, 100%);
  max-height: calc(100vh - 40px);
  overflow-y: auto;
  background: var(--bg-panel);
  border: 1px solid var(--line-mid);
  border-radius: var(--radius-lg);
  padding: 30px 28px 26px;
  text-align: center;
  animation: pop-in 0.25s ease;
  box-shadow: 0 24px 80px rgba(0, 0, 0, 0.6);
}

.modal-close {
  position: absolute;
  top: 14px; right: 16px;
  font-size: 20px;
  color: var(--text-faint);
  width: 32px; height: 32px;
  border-radius: 8px;
  display: grid; place-items: center;
}
.modal-close:hover { color: var(--text-main); background: rgba(255, 255, 255, 0.06); }

.modal-icon {
  width: 52px; height: 52px;
  margin: 0 auto 14px;
  border-radius: 14px;
  display: grid; place-items: center;
  font-size: 24px;
  background: var(--accent-dim);
  border: 1px solid var(--line-mid);
}

.modal h3 { font-size: 19px; font-weight: 600; margin-bottom: 8px; }
.modal .modal-desc { font-size: 13.5px; color: var(--text-sub); margin-bottom: 20px; }

.modal-price { font-size: 15px; color: var(--text-sub); margin-bottom: 20px; }
.modal-price b { font-size: 26px; color: var(--accent); font-weight: 600; }

.modal-steps { text-align: left; list-style: none; margin-bottom: 22px; }
.modal-steps li { font-size: 13.5px; color: var(--text-sub); padding: 8px 0 8px 30px; position: relative; border-bottom: 1px dashed var(--line-soft); }
.modal-steps li:last-child { border-bottom: none; }
.modal-steps .no {
  position: absolute; left: 0; top: 9px;
  width: 20px; height: 20px;
  border-radius: 6px;
  display: grid; place-items: center;
  font-size: 11px; font-weight: 600;
  color: var(--accent);
  background: var(--accent-dim);
  border: 1px solid var(--line-mid);
}

.modal-actions { display: flex; gap: 12px; }
.modal-actions .btn { flex: 1; min-height: 46px; }

/* ---------- 支付码 ---------- */
.pay-box {
  width: 236px;
  max-width: 100%;
  margin: 0 auto 18px;
  padding: 12px 12px 9px;
  background: #fff;
  border-radius: 14px;
  box-shadow: 0 10px 28px rgba(0, 0, 0, 0.38);
}
.pay-qr { display: block; width: 100%; height: auto; border-radius: 8px; }
.pay-brand {
  margin-top: 9px;
  text-align: center;
  font-size: 12px;
  font-weight: 600;
  color: #07a25a;
  letter-spacing: 0.3px;
}
.modal-foot {
  margin-top: 14px;
  text-align: center;
  font-size: 12px;
  line-height: 1.7;
  color: var(--text-faint);
}

.toast {
  position: fixed;
  left: 50%;
  bottom: 42px;
  transform: translateX(-50%) translateY(20px);
  z-index: 120;
  background: var(--bg-panel);
  border: 1px solid var(--accent);
  color: var(--text-main);
  font-size: 13.5px;
  border-radius: var(--radius-md);
  padding: 12px 22px;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s, transform 0.25s;
  box-shadow: 0 12px 40px rgba(0, 0, 0, 0.5);
}
.toast.show { opacity: 1; transform: translateX(-50%) translateY(0); }

/* ---------- 页脚 ---------- */
.footer { border-top: 1px solid var(--line-soft); padding: 30px 0 34px; margin-top: 10px; }

.footer-row { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 12px; font-size: 12.5px; color: var(--text-faint); }
.footer-links { display: flex; gap: 20px; }
.footer-links a:hover { color: var(--accent); }

.icp { margin-top: 12px; font-size: 12.5px; color: var(--text-faint); }
.icp a { color: var(--text-faint); }
.icp a:hover { color: var(--accent); }

/* ---------- 教程文章 ---------- */
.article-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; margin-top: 8px; }
.article-card { display: block; background: var(--bg-card); border: 1px solid var(--line-soft); border-radius: var(--radius-lg); padding: 24px; transition: transform 0.25s, border-color 0.25s; }
.article-card:hover { transform: translateY(-4px); border-color: var(--line-mid); }
.article-tag { display: inline-block; font-size: 12px; color: var(--violet); border: 1px solid rgba(124, 92, 255, 0.4); background: rgba(124, 92, 255, 0.10); border-radius: 999px; padding: 3px 12px; margin-bottom: 14px; }
.article-card h3 { font-size: 17px; line-height: 1.5; margin-bottom: 10px; }
.article-excerpt { color: var(--text-sub); font-size: 13.5px; line-height: 1.65; margin-bottom: 16px; }
.article-meta { display: flex; gap: 14px; font-size: 12.5px; color: var(--text-faint); }
.article { max-width: 820px; margin: 0 auto; }
.article-head { margin-bottom: 24px; padding-bottom: 18px; border-bottom: 1px solid var(--line-soft); }
.article-head h1 { font-size: 28px; line-height: 1.4; margin: 12px 0 14px; }
.article-foot { display: flex; gap: 14px; margin-top: 36px; padding-top: 24px; border-top: 1px solid var(--line-soft); }
.empty { color: var(--text-sub); padding: 40px 0; }

/* 正文排版（文章详情 + 课程免费章共享） */
.article-body, .chapter-content { color: var(--text-sub); font-size: 15px; line-height: 1.85; }
.article-body h3, .chapter-content h3 { color: var(--text-main); font-size: 19px; margin: 28px 0 12px; }
.article-body h4, .chapter-content h4 { color: var(--text-main); font-size: 16px; margin: 22px 0 10px; }
.article-body p, .chapter-content p { margin: 12px 0; }
.article-body ul, .article-body ol, .chapter-content ul, .chapter-content ol { margin: 12px 0; padding-left: 22px; }
.article-body li, .chapter-content li { margin: 6px 0; }
.article-body code, .chapter-content code { background: rgba(0, 229, 204, 0.10); color: var(--accent); padding: 2px 6px; border-radius: 5px; font-size: 13px; font-family: ui-monospace, Menlo, Consolas, monospace; }
.article-body .tip, .chapter-content .tip { margin: 18px 0; padding: 12px 16px; border-left: 3px solid var(--accent); background: var(--accent-dim); border-radius: 0 8px 8px 0; color: var(--text-main); font-size: 14px; }
.article-body .lead, .chapter-content .lead { font-size: 16px; color: var(--text-main); }
.spec-table { width: 100%; border-collapse: collapse; margin: 16px 0; font-size: 13.5px; }
.spec-table th, .spec-table td { border: 1px solid var(--line-soft); padding: 10px 12px; text-align: left; vertical-align: top; }
.spec-table th { background: var(--bg-panel); color: var(--accent); font-weight: 600; }
.spec-table td { color: var(--text-sub); }
.chapter-content { margin-top: 14px; padding-top: 14px; border-top: 1px dashed var(--line-soft); }
.chapter-content pre, .article-body pre { background: var(--bg-deep); border: 1px solid var(--line-soft); border-radius: 8px; padding: 12px 14px; overflow: auto; margin: 14px 0; }
.chapter-content pre code, .article-body pre code { background: none; padding: 0; color: var(--text-main); font-size: 13px; line-height: 1.6; white-space: pre; }

/* 付费章：试读 + 渐隐遮罩 + 解锁 */
.chapter-locked { position: relative; margin-top: 4px; }
.locked-mask { position: absolute; left: 0; right: 0; top: -50px; height: 50px; background: linear-gradient(to bottom, rgba(15, 24, 40, 0), var(--bg-card)); pointer-events: none; }
.locked-tip { text-align: center; padding: 18px 16px; border: 1px dashed var(--line-mid); border-radius: 12px; background: var(--bg-deep); }
.locked-title { color: var(--text-main); font-weight: 600; font-size: 14.5px; margin-bottom: 4px; }
.locked-sub { color: var(--text-sub); font-size: 12.5px; margin-bottom: 12px; }

/* ---------- 适用人群 ---------- */
.who-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 18px; margin-top: 8px; }
.who-card { background: var(--bg-card); border: 1px solid var(--line-soft); border-radius: var(--radius-lg); padding: 24px; transition: transform 0.25s, border-color 0.25s; }
.who-card:hover { transform: translateY(-4px); border-color: var(--line-mid); }
.who-icon { font-size: 26px; color: var(--accent); margin-bottom: 12px; }
.who-card h4 { font-size: 16px; margin-bottom: 8px; }
.who-card p { color: var(--text-sub); font-size: 13.5px; line-height: 1.6; }

/* ---------- 站长说 ---------- */
.story-card { background: linear-gradient(180deg, var(--bg-panel), var(--bg-card)); border: 1px solid var(--line-soft); border-radius: var(--radius-lg); padding: 30px 34px; }
.story-card p { color: var(--text-sub); font-size: 15px; line-height: 1.9; margin: 14px 0; }
.story-card p:first-child { margin-top: 0; }
.story-card strong { color: var(--accent); }

/* ---------- FAQ ---------- */
.faq-list { margin-top: 8px; border-top: 1px solid var(--line-soft); }
.faq-item { border-bottom: 1px solid var(--line-soft); }
.faq-q { width: 100%; display: flex; align-items: center; justify-content: space-between; text-align: left; padding: 20px 4px; font-size: 16px; color: var(--text-main); }
.faq-arrow { color: var(--accent); font-size: 20px; transition: transform 0.25s; }
.faq-item.open .faq-arrow { transform: rotate(45deg); }
.faq-a { max-height: 0; overflow: hidden; transition: max-height 0.3s ease; }
.faq-a p { padding: 0 4px 20px; color: var(--text-sub); font-size: 14px; line-height: 1.8; }
.faq-item.open .faq-a { max-height: 220px; }

/* ---------- 动画 ---------- */
@keyframes fade-up { from { opacity: 0; transform: translateY(18px); } to { opacity: 1; transform: none; } }
@keyframes mask-in { from { opacity: 0; } to { opacity: 1; } }
@keyframes pop-in { from { opacity: 0; transform: scale(0.94) translateY(10px); } to { opacity: 1; transform: none; } }
@keyframes pulse { 0%, 100% { opacity: 1; } 50% { opacity: 0.35; } }

.reveal { opacity: 0; transform: translateY(22px); transition: opacity 0.6s ease, transform 0.6s ease; }
.reveal.in { opacity: 1; transform: none; }

/* ---------- 响应式 ---------- */
@media (max-width: 900px) {
  .course-layout { grid-template-columns: 1fr; }
  .buy-box { position: static; }
  .course-grid { grid-template-columns: 1fr; }
  .why-grid { grid-template-columns: 1fr; }
  .article-grid { grid-template-columns: 1fr; }
  .who-grid { grid-template-columns: 1fr; }
  .story-card { padding: 22px; }
  .article-head h1 { font-size: 22px; }
  .article-foot { flex-wrap: wrap; }
  .stats { grid-template-columns: repeat(2, 1fr); }
  .hero h1 { font-size: 32px; }
  .nav-links { display: none; }
}

@media (max-width: 520px) {
  .modal-mask { padding: 12px; }
  .modal { width: 100%; max-width: 100%; padding: 26px 18px 20px; }
  .modal-price b { font-size: 23px; }
  .pay-box { width: 100%; max-width: 210px; }
  .modal-foot { font-size: 11.5px; }
}