/* ============================================================
   砚知学堂 / 互选学习网 - 全站样式表 v2.0
   设计: 阿屿 | 2026-09-08
   ============================================================ */

/* ---------- 变量 & 重置 ---------- */
:root {
  --primary: #1A73E8;
  --primary-dark: #0D47A1;
  --primary-light: #E8F0FE;
  --accent: #FF6B35;
  --accent-light: #FFF0EB;
  --success: #00C853;
  --success-light: #E8F5E9;
  --gray-50: #fafbfc;
  --gray-100: #f5f7fa;
  --gray-200: #e8eaed;
  --gray-300: #dadce0;
  --gray-500: #9aa0a6;
  --gray-700: #5f6368;
  --gray-900: #202124;
  --white: #ffffff;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.08);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.1);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.12);
  --shadow-xl: 0 16px 48px rgba(0,0,0,0.16);
  --radius: 12px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --transition: 0.25s ease;
}

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

html { scroll-behavior: smooth; font-size: 16px; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif;
  line-height: 1.65;
  color: var(--gray-900);
  background: var(--white);
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; display: block; }
a { text-decoration: none; color: inherit; }
ul { list-style: none; }
button { cursor: pointer; border: none; background: none; font-family: inherit; }

/* ---------- 布局 ---------- */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.section {
  padding: 80px 0;
}

.section-header {
  text-align: center;
  margin-bottom: 48px;
}

.section-title {
  font-size: 30px;
  font-weight: 700;
  color: var(--gray-900);
  margin-bottom: 12px;
  letter-spacing: -0.5px;
}

.section-sub {
  font-size: 16px;
  color: var(--gray-500);
  max-width: 560px;
  margin: 0 auto;
}

.section-header-row {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  margin-bottom: 32px;
  flex-wrap: wrap;
  gap: 12px;
}

/* ---------- 按钮 ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 12px 24px;
  border-radius: var(--radius);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  border: 2px solid transparent;
  white-space: nowrap;
  font-family: inherit;
  text-decoration: none;
}

.btn-primary { background: var(--primary); color: white; border-color: var(--primary); }
.btn-primary:hover { background: var(--primary-dark); border-color: var(--primary-dark); transform: translateY(-1px); box-shadow: var(--shadow-md); color: white; }

.btn-outline { background: transparent; border-color: var(--primary); color: var(--primary); }
.btn-outline:hover { background: var(--primary); color: white; }

.btn-white { background: white; color: var(--primary); border-color: white; }
.btn-white:hover { background: var(--gray-100); transform: translateY(-2px); box-shadow: var(--shadow-lg); }

.btn-outline-white { background: transparent; border-color: white; color: white; }
.btn-outline-white:hover { background: rgba(255,255,255,0.15); }

.btn-sm { padding: 8px 16px; font-size: 13px; border-radius: 8px; }
.btn-lg { padding: 16px 36px; font-size: 16px; border-radius: var(--radius-lg); }

/* ---------- 头部导航 ---------- */
.header {
  position: fixed;
  top: 0; left: 0; right: 0;
  background: rgba(255,255,255,0.97);
  backdrop-filter: blur(12px);
  box-shadow: var(--shadow-sm);
  z-index: 1000;
  transition: box-shadow var(--transition);
}

.header.scrolled { box-shadow: var(--shadow-md); }

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
  gap: 24px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 20px;
  font-weight: 700;
  color: var(--primary);
  text-decoration: none;
  flex-shrink: 0;
}

.logo-icon {
  font-size: 24px;
  width: 38px; height: 38px;
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  color: white;
  flex-shrink: 0;
}

.logo-text { font-size: 20px; }

.nav {
  display: flex;
  align-items: center;
  gap: 4px;
  flex: 1;
  justify-content: center;
}

.nav a {
  color: var(--gray-700);
  font-size: 14px;
  font-weight: 500;
  padding: 6px 12px;
  border-radius: 8px;
  transition: all var(--transition);
  position: relative;
}

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

.header-actions { flex-shrink: 0; }

.nav-toggle { display: none; }

/* ---------- 移动端菜单 ---------- */
.mobile-nav {
  position: fixed;
  top: 0; right: -100%;
  width: min(320px, 85vw);
  height: 100vh;
  background: white;
  z-index: 2000;
  transition: right 0.35s ease;
  box-shadow: var(--shadow-xl);
  overflow-y: auto;
}

.mobile-nav.open { right: 0; }

.mobile-nav-inner { padding: 20px; }

.mobile-nav-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 24px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--gray-200);
}

.mobile-nav-header .logo-text { font-size: 18px; font-weight: 700; color: var(--primary); }

.nav-close { font-size: 22px; color: var(--gray-500); padding: 4px; }

.mobile-nav a {
  display: block;
  padding: 12px 8px;
  font-size: 15px;
  color: var(--gray-700);
  border-bottom: 1px solid var(--gray-100);
  transition: all var(--transition);
}

.mobile-nav a:hover { color: var(--primary); background: var(--primary-light); padding-left: 16px; }

.mobile-nav-cta { margin-top: 20px; }

.mobile-nav-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  z-index: 1999;
  display: none;
}

/* 移动端固定底部CTA */
.mobile-cta {
  display: none;
  position: fixed;
  bottom: 0; left: 0; right: 0;
  background: white;
  box-shadow: 0 -2px 16px rgba(0,0,0,0.1);
  padding: 10px 16px;
  gap: 10px;
  z-index: 999;
  justify-content: space-between;
}

.mobile-cta-btn {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 12px;
  background: var(--primary);
  color: white;
  font-size: 14px;
  font-weight: 600;
  border-radius: var(--radius);
}

.mobile-cta-btn-secondary {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 12px;
  background: var(--gray-100);
  color: var(--gray-700);
  font-size: 14px;
  font-weight: 600;
  border-radius: var(--radius);
  border: 1px solid var(--gray-300);
}

/* ---------- HERO ---------- */
.hero {
  margin-top: 68px;
  background: linear-gradient(135deg, #0D47A1 0%, #1A73E8 50%, #2196F3 100%);
  color: white;
  position: relative;
  overflow: hidden;
  padding: 80px 0 90px;
}

.hero-bg-pattern {
  position: absolute;
  inset: 0;
  background-image:
    radial-gradient(circle at 20% 50%, rgba(255,255,255,0.08) 0%, transparent 50%),
    radial-gradient(circle at 80% 20%, rgba(255,255,255,0.06) 0%, transparent 40%),
    radial-gradient(circle at 60% 80%, rgba(255,255,255,0.05) 0%, transparent 35%);
  pointer-events: none;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 60%;
  height: 200%;
  background: radial-gradient(ellipse, rgba(255,255,255,0.06) 0%, transparent 70%);
  pointer-events: none;
}

.hero-inner {
  position: relative;
  text-align: center;
  max-width: 760px;
  margin: 0 auto;
}

.hero-badge {
  display: inline-block;
  background: rgba(255,255,255,0.15);
  border: 1px solid rgba(255,255,255,0.3);
  padding: 6px 18px;
  border-radius: 20px;
  font-size: 13px;
  font-weight: 600;
  margin-bottom: 24px;
  letter-spacing: 0.5px;
}

.hero-title {
  font-size: clamp(32px, 5vw, 54px);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 16px;
  letter-spacing: -1px;
}

.hero-title .highlight {
  color: #FFD54F;
}

.hero-sub {
  font-size: 18px;
  opacity: 0.95;
  margin-bottom: 8px;
  color: rgba(255,255,255,0.9);
}

.hero-brand {
  font-size: 15px;
  opacity: 0.7;
  margin-bottom: 36px;
  font-weight: 500;
}

.hero-stats {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 40px;
  margin: 0 auto 36px;
  background: rgba(255,255,255,0.1);
  border: 1px solid rgba(255,255,255,0.2);
  border-radius: var(--radius-xl);
  padding: 20px 40px;
  width: fit-content;
}

.stat-item { text-align: center; }
.stat-num { font-size: 36px; font-weight: 800; display: block; color: #FFD54F; line-height: 1.1; }
.stat-label { font-size: 13px; opacity: 0.85; margin-top: 2px; }

.stat-divider {
  width: 1px;
  height: 40px;
  background: rgba(255,255,255,0.25);
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 14px;
  margin-bottom: 28px;
  flex-wrap: wrap;
}

.hero-actions .btn { padding: 14px 32px; font-size: 15px; border-radius: var(--radius-lg); }

.hero-trust {
  display: flex;
  justify-content: center;
  gap: 20px;
  font-size: 13px;
  opacity: 0.8;
  flex-wrap: wrap;
}

/* ---------- 品牌展示 ---------- */
.brands-section { background: var(--gray-50); }

.brands-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.brand-card {
  background: white;
  border-radius: var(--radius-xl);
  padding: 32px 28px;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition);
  border: 2px solid transparent;
  display: flex;
  flex-direction: column;
}

.brand-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.brand-peiyou { border-top: 4px solid var(--primary); }
.brand-dzt { border-top: 4px solid var(--success); }
.brand-zhihui { border-top: 4px solid var(--accent); }

.brand-card-header {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-bottom: 16px;
}

.brand-icon { font-size: 40px; }

.brand-meta {}

.brand-tag {
  display: inline-block;
  font-size: 11px;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 20px;
  margin-bottom: 4px;
  letter-spacing: 0.5px;
}

.brand-peiyou .brand-tag { background: var(--primary-light); color: var(--primary); }
.brand-dzt .brand-tag { background: var(--success-light); color: #00801a; }
.brand-zhihui .brand-tag { background: var(--accent-light); color: var(--accent); }

.brand-name { font-size: 22px; font-weight: 700; color: var(--gray-900); }

.brand-desc {
  font-size: 14px;
  color: var(--gray-700);
  line-height: 1.7;
  margin-bottom: 16px;
  flex: 1;
}

.brand-features { margin-bottom: 20px; flex: 1; }
.brand-features li {
  font-size: 13px;
  color: var(--gray-700);
  padding: 4px 0;
  padding-left: 4px;
}

.brand-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 16px;
  border-top: 1px solid var(--gray-200);
}

.brand-count { font-size: 13px; color: var(--gray-500); font-weight: 500; }

.btn-brand-peiyou { background: var(--primary); color: white; border-color: var(--primary); font-size: 13px; padding: 8px 18px; }
.btn-brand-peiyou:hover { background: var(--primary-dark); color: white; }

.btn-brand-dzt { background: var(--success); color: white; border-color: var(--success); font-size: 13px; padding: 8px 18px; }
.btn-brand-dzt:hover { background: #00992e; color: white; }

.btn-brand-zhihui { background: var(--accent); color: white; border-color: var(--accent); font-size: 13px; padding: 8px 18px; }
.btn-brand-zhihui:hover { background: #e55a26; color: white; }

/* ---------- 产品类型 ---------- */
.products-type-section { background: white; }

.types-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.type-card {
  background: var(--gray-50);
  border-radius: var(--radius-xl);
  padding: 32px 24px;
  text-align: center;
  transition: all var(--transition);
  border: 2px solid transparent;
}

.type-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary);
}

.type-card.type-card-accent {
  background: linear-gradient(135deg, var(--primary-light), #e3f2fd);
  border-color: var(--primary);
}

.type-icon { font-size: 48px; margin-bottom: 16px; }

.type-card h3 { font-size: 18px; font-weight: 700; color: var(--gray-900); margin-bottom: 10px; }

.type-card p { font-size: 13px; color: var(--gray-700); line-height: 1.65; margin-bottom: 16px; }

.type-link { font-size: 13px; font-weight: 600; color: var(--primary); }
.type-link:hover { color: var(--primary-dark); }

/* ---------- 年级导航 ---------- */
.grades-section { background: var(--gray-50); }

.grade-nav { display: flex; flex-direction: column; gap: 16px; }

.grade-group { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }

.grade-group-label {
  font-size: 13px;
  font-weight: 700;
  color: var(--gray-500);
  min-width: 40px;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.grade-btn {
  padding: 10px 22px;
  border-radius: 30px;
  font-size: 14px;
  font-weight: 600;
  background: white;
  color: var(--gray-700);
  border: 2px solid var(--gray-300);
  transition: all var(--transition);
  text-decoration: none;
  display: inline-block;
}

.grade-btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.grade-btn.grade-primary { border-color: #4CAF50; color: #388E3C; }
.grade-btn.grade-primary:hover { background: #4CAF50; color: white; border-color: #4CAF50; }

.grade-btn.grade-junior { border-color: var(--accent); color: var(--accent); }
.grade-btn.grade-junior:hover { background: var(--accent); color: white; border-color: var(--accent); }

.badge-zk {
  display: inline-block;
  background: var(--accent);
  color: white;
  font-size: 10px;
  padding: 1px 6px;
  border-radius: 10px;
  margin-left: 4px;
}

/* ---------- 热门产品 ---------- */
.hot-products-section { background: white; }

.product-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.product-card {
  background: white;
  border-radius: var(--radius-xl);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--gray-200);
  transition: all var(--transition);
}

.product-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
  border-color: transparent;
}

.product-img {
  height: 180px;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
}

.product-img-1 { background: linear-gradient(135deg, #1565C0, #1976D2); }
.product-img-2 { background: linear-gradient(135deg, #2E7D32, #388E3C); }
.product-img-3 { background: linear-gradient(135deg, #F57F17, #F9A825); }
.product-img-4 { background: linear-gradient(135deg, #6A1B9A, #8E24AA); }
.product-img-5 { background: linear-gradient(135deg, #00838F, #00ACC1); }
.product-img-6 { background: linear-gradient(135deg, #AD1457, #D81B60); }
.product-img-7 { background: linear-gradient(135deg, #EF6C00, #FB8C00); }
.product-img-8 { background: linear-gradient(135deg, #00695C, #00897B); }

.product-img-text {
  font-size: 16px;
  font-weight: 700;
  color: white;
  text-align: center;
  line-height: 1.4;
  text-shadow: 0 1px 4px rgba(0,0,0,0.3);
}

.product-info { padding: 18px; }

.product-tags { display: flex; gap: 6px; margin-bottom: 10px; flex-wrap: wrap; }

.tag {
  padding: 3px 9px;
  border-radius: 12px;
  font-size: 11px;
  font-weight: 600;
  background: var(--gray-100);
  color: var(--gray-700);
}

.tag.tag-primary { background: #E3F2FD; color: var(--primary); }
.tag.tag-junior { background: #FFF3E0; color: var(--accent); }
.tag.tag-hot { background: #FFEBEE; color: #C62828; }
.tag.tag-new { background: var(--success-light); color: #1B5E20; }

.product-title { font-size: 15px; font-weight: 700; color: var(--gray-900); margin-bottom: 8px; line-height: 1.4; }

.product-desc { font-size: 12px; color: var(--gray-500); line-height: 1.6; margin-bottom: 14px; }

.product-footer { display: flex; gap: 8px; }
.product-footer .btn { flex: 1; font-size: 12px; padding: 7px 8px; }

/* ---------- 扫码学习专区 ---------- */
.scan-section {
  background: linear-gradient(135deg, #0D47A1 0%, #1565C0 50%, #1976D2 100%);
  color: white;
  padding: 80px 0;
}

.scan-wrapper {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 60px;
  align-items: center;
}

.scan-badge {
  display: inline-block;
  background: rgba(255,255,255,0.2);
  border: 1px solid rgba(255,255,255,0.3);
  padding: 4px 14px;
  border-radius: 20px;
  font-size: 12px;
  font-weight: 600;
  margin-bottom: 20px;
}

.scan-title { font-size: 30px; font-weight: 800; margin-bottom: 16px; }

.scan-desc { font-size: 15px; opacity: 0.9; line-height: 1.7; margin-bottom: 24px; }

.scan-features { margin-bottom: 28px; }
.scan-features li {
  font-size: 14px;
  padding: 6px 0;
  opacity: 0.9;
}
.scan-features strong { color: #FFD54F; }

.scan-actions .btn { padding: 14px 32px; font-size: 15px; border-radius: var(--radius-lg); }

/* 手机模拟 */
.scan-phone {
  background: #1a1a2e;
  border-radius: 36px;
  padding: 16px;
  box-shadow: 0 20px 60px rgba(0,0,0,0.4);
  border: 2px solid #333;
}

.scan-phone-screen {
  background: white;
  border-radius: 26px;
  overflow: hidden;
}

.scan-screen-content { padding: 16px; }

.scan-screen-title {
  font-size: 13px;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 12px;
  text-align: center;
}

.scan-screen-items { display: flex; flex-direction: column; gap: 8px; margin-bottom: 16px; }

.scan-screen-item {
  background: var(--primary-light);
  padding: 10px 14px;
  border-radius: 10px;
  font-size: 13px;
  color: var(--gray-900);
}

.scan-screen-item:first-child { background: #E3F2FD; font-weight: 600; }

.scan-screen-playing {
  border-top: 1px solid var(--gray-200);
  padding-top: 10px;
}

.playing-bar {
  height: 4px;
  background: var(--gray-200);
  border-radius: 2px;
  margin-bottom: 6px;
}

.playing-bar-inner {
  height: 100%;
  background: var(--primary);
  border-radius: 2px;
}

.playing-time { font-size: 11px; color: var(--gray-500); text-align: right; }

/* ---------- 核心优势 ---------- */
.features-section { background: var(--gray-50); }

.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.feature-card {
  background: white;
  border-radius: var(--radius-xl);
  padding: 32px 28px;
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition);
  border: 1px solid var(--gray-200);
}

.feature-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary);
}

.feature-icon { font-size: 44px; margin-bottom: 16px; }
.feature-card h3 { font-size: 18px; font-weight: 700; margin-bottom: 10px; color: var(--gray-900); }
.feature-card p { font-size: 14px; color: var(--gray-500); line-height: 1.65; }

/* ---------- 家长评价 ---------- */
.reviews-section { background: white; }

.reviews-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.review-card {
  background: var(--gray-50);
  border-radius: var(--radius-xl);
  padding: 28px 24px;
  border: 1px solid var(--gray-200);
  transition: all var(--transition);
}

.review-card:hover {
  border-color: var(--primary);
  box-shadow: var(--shadow-md);
}

.review-stars { color: #FFC107; font-size: 18px; margin-bottom: 14px; letter-spacing: 2px; }

.review-text {
  font-size: 14px;
  color: var(--gray-700);
  line-height: 1.75;
  margin-bottom: 20px;
  font-style: italic;
}

.review-author { display: flex; align-items: center; gap: 12px; }

.review-avatar {
  width: 40px; height: 40px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: white;
  display: flex; align-items: center; justify-content: center;
  font-weight: 700;
  font-size: 16px;
  flex-shrink: 0;
}

.review-info { display: flex; flex-direction: column; }
.review-name { font-size: 14px; font-weight: 700; color: var(--gray-900); }
.review-meta { font-size: 12px; color: var(--gray-500); }

/* ---------- CTA ---------- */
.cta-section {
  background: linear-gradient(135deg, var(--primary) 0%, var(--primary-dark) 100%);
  color: white;
  padding: 80px 0;
}

.cta-wrapper { text-align: center; }

.cta-title { font-size: 36px; font-weight: 800; margin-bottom: 12px; }
.cta-sub { font-size: 17px; opacity: 0.9; margin-bottom: 48px; }

.cta-items {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.cta-item {
  background: rgba(255,255,255,0.12);
  border: 1px solid rgba(255,255,255,0.2);
  border-radius: var(--radius-xl);
  padding: 32px 24px;
  text-align: center;
  transition: all var(--transition);
}

.cta-item:hover { background: rgba(255,255,255,0.2); transform: translateY(-3px); }

.cta-icon { font-size: 40px; margin-bottom: 16px; }
.cta-item h4 { font-size: 18px; font-weight: 700; margin-bottom: 8px; }
.cta-item p { font-size: 13px; opacity: 0.8; margin-bottom: 20px; }
.cta-item .btn { width: 100%; justify-content: center; }

/* ---------- 页脚 ---------- */
.footer {
  background: var(--gray-900);
  color: var(--gray-500);
  padding: 60px 0 0;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 48px;
  padding-bottom: 40px;
}

.footer-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 20px;
  font-weight: 700;
  color: white;
  margin-bottom: 14px;
}

.footer-desc { font-size: 13px; line-height: 1.7; margin-bottom: 16px; }

.footer-social img { border-radius: 8px; }

.footer-col h4 {
  color: white;
  font-size: 14px;
  font-weight: 700;
  margin-bottom: 16px;
}

.footer-col ul li { margin-bottom: 8px; }
.footer-col ul li a {
  font-size: 13px;
  color: var(--gray-500);
  transition: color var(--transition);
}
.footer-col ul li a:hover { color: white; }

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.1);
  padding: 20px 0;
  text-align: center;
  font-size: 12px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.footer-bottom p { margin: 0; }
.footer-bottom a { color: var(--gray-500); }
.footer-bottom a:hover { color: white; }

/* ---------- 响应式 ---------- */
@media (max-width: 1024px) {
  .product-grid { grid-template-columns: repeat(3, 1fr); }
  .footer-grid { grid-template-columns: repeat(2, 1fr); gap: 32px; }
  .scan-wrapper { grid-template-columns: 1fr 280px; gap: 40px; }
}

@media (max-width: 900px) {
  .nav { display: none; }
  .header-actions { display: none; }
  .nav-toggle { display: block; font-size: 24px; color: var(--gray-700); padding: 4px; }

  .brands-grid { grid-template-columns: 1fr; gap: 16px; }
  .product-grid { grid-template-columns: repeat(2, 1fr); gap: 14px; }
  .types-grid { grid-template-columns: repeat(2, 1fr); gap: 14px; }
  .feature-grid { grid-template-columns: repeat(2, 1fr); gap: 16px; }
  .reviews-grid { grid-template-columns: 1fr; }
  .cta-items { grid-template-columns: 1fr; gap: 16px; }
  .scan-wrapper { grid-template-columns: 1fr; }
  .scan-visual { display: none; }
  .section { padding: 60px 0; }
}

@media (max-width: 600px) {
  .hero { padding: 60px 0 70px; }
  .hero-stats { padding: 16px 24px; gap: 24px; }
  .stat-num { font-size: 28px; }
  .hero-actions { flex-direction: column; align-items: center; }
  .hero-actions .btn { width: 240px; justify-content: center; }
  .hero-trust { flex-direction: column; align-items: center; gap: 8px; }

  .brands-grid,
  .product-grid,
  .feature-grid,
  .types-grid { grid-template-columns: 1fr; }

  .product-grid { gap: 12px; }
  .product-img { height: 150px; }

  .grade-nav { gap: 12px; }
  .grade-group { gap: 8px; }
  .grade-btn { padding: 8px 16px; font-size: 13px; }

  .section-title { font-size: 24px; }
  .scan-title { font-size: 24px; }
  .cta-title { font-size: 26px; }
  .cta-items { gap: 12px; }
  .cta-item { padding: 24px 20px; }

  .footer-grid { grid-template-columns: 1fr; gap: 28px; }

  .mobile-cta { display: flex; }
  body { padding-bottom: 70px; }

  .section { padding: 48px 0; }
  .section-header { margin-bottom: 32px; }
  .section-header-row { flex-direction: column; align-items: flex-start; }
}

/* ---------- 微交互动画 ---------- */
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

.feature-card, .brand-card, .type-card, .product-card, .review-card, .cta-item {
  animation: fadeInUp 0.5s ease both;
}

.feature-grid .feature-card:nth-child(1) { animation-delay: 0.05s; }
.feature-grid .feature-card:nth-child(2) { animation-delay: 0.1s; }
.feature-grid .feature-card:nth-child(3) { animation-delay: 0.15s; }
.feature-grid .feature-card:nth-child(4) { animation-delay: 0.2s; }
.feature-grid .feature-card:nth-child(5) { animation-delay: 0.25s; }
.feature-grid .feature-card:nth-child(6) { animation-delay: 0.3s; }

/* 按钮点击波纹效果 */
.btn:active { transform: scale(0.97); }

/* 焦点样式（无障碍） */
a:focus-visible, button:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 2px;
}

/* 选中文字颜色 */
::selection { background: var(--primary); color: white; }