:root {
  --brand-primary: #1a3a4a;
  --brand-secondary: #e8b84b;
  --brand-accent: #c0392b;
  --brand-light: #f5f7f8;
  --brand-dark: #0f1f28;
  --text-main: #1e2b32;
  --text-secondary: #4a5a62;
  --text-muted: #6b7b83;
  --bg-body: #ffffff;
  --bg-card: #ffffff;
  --bg-alt: #f0f4f6;
  --border-color: #dce4e8;
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 6px 20px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 12px 36px rgba(0, 0, 0, 0.14);
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --transition: 0.25s ease;
  --max-width: 1200px;
  --header-height: 68px;
  --glass-bg: rgba(255, 255, 255, 0.72);
  --glass-border: rgba(255, 255, 255, 0.35);
  --glass-blur: 16px;
  --gradient-1: linear-gradient(135deg, #1a3a4a 0%, #2a5a6a 50%, #0f1f28 100%);
  --gradient-2: linear-gradient(135deg, #2a1a3a 0%, #4a2a5a 50%, #0f0f1f 100%);
  --gradient-3: linear-gradient(135deg, #1a3a2a 0%, #2a5a3a 50%, #0f1f18 100%);
  --gradient-accent: linear-gradient(135deg, #e8b84b 0%, #f0c96b 100%);
}

body.dark-mode {
  --brand-primary: #7ab7d4;
  --brand-secondary: #f0c96b;
  --brand-accent: #e74c3c;
  --brand-light: #1e2b32;
  --brand-dark: #0b1418;
  --text-main: #e8edef;
  --text-secondary: #b0c0c8;
  --text-muted: #7a8a92;
  --bg-body: #121a1f;
  --bg-card: #1a242b;
  --bg-alt: #1e2b32;
  --border-color: #2a3a42;
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-md: 0 6px 20px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 12px 36px rgba(0, 0, 0, 0.5);
  --glass-bg: rgba(26, 36, 43, 0.72);
  --glass-border: rgba(255, 255, 255, 0.08);
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  background-color: var(--bg-body);
  color: var(--text-main);
  line-height: 1.75;
  transition: background-color var(--transition), color var(--transition);
  padding-top: var(--header-height);
  overflow-x: hidden;
}

a {
  color: var(--brand-primary);
  text-decoration: none;
  transition: color var(--transition);
}

a:hover {
  color: var(--brand-secondary);
}

img, svg {
  max-width: 100%;
  height: auto;
  display: block;
}

ul, ol {
  list-style: none;
}

button {
  font-family: inherit;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* ========== 头部导航 ========== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: var(--glass-bg);
  -webkit-backdrop-filter: blur(var(--glass-blur));
  backdrop-filter: blur(var(--glass-blur));
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
  transition: box-shadow var(--transition), background var(--transition);
}

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

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.35rem;
  color: var(--brand-primary);
  letter-spacing: -0.02em;
  flex-shrink: 0;
}

.logo svg {
  width: 36px;
  height: 36px;
  flex-shrink: 0;
  transition: transform var(--transition);
}

.logo:hover svg {
  transform: rotate(-6deg) scale(1.06);
}

.main-nav {
  display: flex;
  align-items: center;
  gap: 4px;
}

.main-nav a {
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-secondary);
  transition: background var(--transition), color var(--transition), transform var(--transition);
  position: relative;
}

.main-nav a:hover,
.main-nav a.active {
  background: var(--brand-light);
  color: var(--brand-primary);
  transform: translateY(-1px);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 10px;
}

.search-box {
  display: flex;
  align-items: center;
  background: var(--bg-alt);
  border-radius: 24px;
  padding: 6px 14px;
  border: 1px solid var(--border-color);
  transition: border-color var(--transition), box-shadow var(--transition);
}

.search-box:focus-within {
  border-color: var(--brand-primary);
  box-shadow: 0 0 0 3px rgba(26, 58, 74, 0.12);
}

.search-box input {
  border: none;
  background: transparent;
  outline: none;
  font-size: 0.9rem;
  color: var(--text-main);
  width: 140px;
  font-family: inherit;
  transition: width var(--transition);
}

.search-box input::placeholder {
  color: var(--text-muted);
}

.search-box button {
  background: none;
  border: none;
  cursor: pointer;
  padding: 2px;
  color: var(--text-muted);
  display: flex;
  align-items: center;
  transition: color var(--transition), transform var(--transition);
}

.search-box button:hover {
  color: var(--brand-primary);
  transform: scale(1.12);
}

.theme-toggle {
  background: var(--bg-alt);
  border: 1px solid var(--border-color);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  color: var(--text-secondary);
  transition: background var(--transition), color var(--transition), transform var(--transition), box-shadow var(--transition);
  flex-shrink: 0;
}

.theme-toggle:hover {
  background: var(--brand-light);
  color: var(--brand-primary);
  transform: rotate(24deg) scale(1.06);
  box-shadow: var(--shadow-sm);
}

.mobile-menu-btn {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  color: var(--text-main);
  padding: 8px;
  border-radius: var(--radius-sm);
  transition: background var(--transition);
}

.mobile-menu-btn:hover {
  background: var(--brand-light);
}

/* ========== 移动菜单 ========== */
.mobile-nav {
  display: none;
  position: fixed;
  top: var(--header-height);
  left: 0;
  right: 0;
  background: var(--glass-bg);
  -webkit-backdrop-filter: blur(var(--glass-blur));
  backdrop-filter: blur(var(--glass-blur));
  border-bottom: 1px solid var(--border-color);
  box-shadow: var(--shadow-md);
  padding: 12px 20px 20px;
  z-index: 999;
  flex-direction: column;
  gap: 4px;
  animation: slideDown 0.28s ease;
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.mobile-nav.open {
  display: flex;
}

.mobile-nav a {
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  font-weight: 500;
  color: var(--text-secondary);
  transition: background var(--transition), color var(--transition), padding-left var(--transition);
}

.mobile-nav a:hover {
  background: var(--brand-light);
  color: var(--brand-primary);
  padding-left: 22px;
}

/* ========== 面包屑 ========== */
.breadcrumb {
  padding: 16px 0;
  font-size: 0.88rem;
  color: var(--text-muted);
}

.breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  align-items: center;
}

.breadcrumb li {
  display: flex;
  align-items: center;
  gap: 6px;
}

.breadcrumb li::after {
  content: "›";
  color: var(--text-muted);
  font-size: 1rem;
}

.breadcrumb li:last-child::after {
  display: none;
}

.breadcrumb a {
  color: var(--text-muted);
}

.breadcrumb a:hover {
  color: var(--brand-primary);
}

.breadcrumb .current {
  color: var(--text-main);
  font-weight: 500;
}

/* ========== Banner 轮播 ========== */
.banner-section {
  position: relative;
  margin: 0 0 40px;
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: var(--brand-dark);
  min-height: 420px;
  box-shadow: var(--shadow-lg);
}

.banner-slides {
  position: relative;
  width: 100%;
  height: 100%;
  min-height: 420px;
}

.banner-slide {
  position: absolute;
  inset: 0;
  opacity: 0;
  transition: opacity 0.8s ease;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 60px 40px;
  pointer-events: none;
}

.banner-slide.active {
  opacity: 1;
  pointer-events: auto;
  position: relative;
}

.banner-slide svg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.15;
}

.banner-slide::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 30% 40%, rgba(232, 184, 75, 0.12), transparent 55%);
  pointer-events: none;
}

.banner-content {
  position: relative;
  z-index: 2;
  text-align: center;
  max-width: 760px;
  animation: fadeUp 0.9s ease both;
}

@keyframes fadeUp {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.banner-content h2 {
  font-size: 2.2rem;
  color: #fff;
  margin-bottom: 16px;
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.3;
  text-shadow: 0 2px 20px rgba(0, 0, 0, 0.3);
}

.banner-content p {
  font-size: 1.1rem;
  color: rgba(255, 255, 255, 0.85);
  margin-bottom: 28px;
  line-height: 1.7;
}

.banner-cta {
  display: inline-block;
  background: var(--gradient-accent);
  color: var(--brand-dark);
  padding: 12px 32px;
  border-radius: 40px;
  font-weight: 700;
  font-size: 1rem;
  transition: transform var(--transition), box-shadow var(--transition);
  box-shadow: 0 4px 16px rgba(232, 184, 75, 0.3);
}

.banner-cta:hover {
  transform: translateY(-3px) scale(1.03);
  box-shadow: 0 10px 28px rgba(232, 184, 75, 0.5);
  color: var(--brand-dark);
}

.banner-dots {
  position: absolute;
  bottom: 20px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  gap: 10px;
  z-index: 5;
}

.banner-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.4);
  border: none;
  cursor: pointer;
  transition: background var(--transition), transform var(--transition), width var(--transition);
  padding: 0;
}

.banner-dot.active {
  background: var(--brand-secondary);
  transform: scale(1.2);
  width: 26px;
  border-radius: 6px;
}

/* ========== 数字统计 ========== */
.stats-section {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  margin: 0 0 48px;
}

.stat-card {
  background: var(--glass-bg);
  -webkit-backdrop-filter: blur(var(--glass-blur));
  backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 28px 20px;
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}

.stat-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-md);
  border-color: var(--brand-secondary);
}

.stat-number {
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--brand-primary);
  line-height: 1.2;
  letter-spacing: -0.02em;
  background: linear-gradient(135deg, var(--brand-primary), var(--brand-secondary));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.stat-label {
  font-size: 0.92rem;
  color: var(--text-muted);
  margin-top: 6px;
}

/* ========== 通用区块 ========== */
.section {
  margin-bottom: 56px;
}

.section-header {
  margin-bottom: 28px;
}

.section-header h2 {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text-main);
  letter-spacing: -0.01em;
  margin-bottom: 8px;
  position: relative;
  padding-left: 18px;
}

.section-header h2::before {
  content: "";
  position: absolute;
  left: 0;
  top: 6px;
  bottom: 6px;
  width: 5px;
  border-radius: 3px;
  background: var(--gradient-accent);
}

.section-header p {
  color: var(--text-secondary);
  font-size: 1rem;
  padding-left: 18px;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  gap: 24px;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 28px 24px;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  position: relative;
  overflow: hidden;
}

.card::after {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--gradient-accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform var(--transition);
}

.card:hover::after {
  transform: scaleX(1);
}

.card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-md);
  border-color: var(--brand-secondary);
}

.card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--text-main);
}

.card p {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.card-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-sm);
  background: var(--brand-light);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
  color: var(--brand-primary);
  transition: background var(--transition), color var(--transition), transform var(--transition);
}

.card:hover .card-icon {
  background: var(--gradient-accent);
  color: var(--brand-dark);
  transform: rotate(-6deg) scale(1.08);
}

/* ========== 文章列表 ========== */
.article-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 24px;
}

.article-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition);
  display: flex;
  flex-direction: column;
}

.article-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-md);
}

.article-thumb {
  height: 160px;
  background: var(--brand-light);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
  position: relative;
}

.article-thumb svg {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.5s ease;
}

.article-card:hover .article-thumb svg {
  transform: scale(1.06);
}

.article-body {
  padding: 20px 22px 24px;
  display: flex;
  flex-direction: column;
  flex: 1;
}

.article-meta {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-bottom: 8px;
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.article-body h3 {
  font-size: 1.08rem;
  font-weight: 700;
  margin-bottom: 10px;
  color: var(--text-main);
  line-height: 1.45;
}

.article-body p {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.65;
  flex: 1;
  margin-bottom: 14px;
}

.read-more {
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--brand-primary);
  display: inline-flex;
  align-items: center;
  gap: 4px;
  transition: gap var(--transition), color var(--transition);
}

.read-more:hover {
  gap: 8px;
  color: var(--brand-secondary);
}

/* ========== FAQ 手风琴 ========== */
.faq-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  overflow: hidden;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.faq-item:hover {
  box-shadow: var(--shadow-sm);
}

.faq-item.open {
  border-color: var(--brand-secondary);
  box-shadow: var(--shadow-sm);
}

.faq-question {
  width: 100%;
  background: none;
  border: none;
  padding: 18px 22px;
  text-align: left;
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-main);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  font-family: inherit;
  transition: background var(--transition), color var(--transition);
}

.faq-question:hover {
  background: var(--brand-light);
  color: var(--brand-primary);
}

.faq-question svg {
  flex-shrink: 0;
  transition: transform var(--transition);
  color: var(--text-muted);
}

.faq-item.open .faq-question svg {
  transform: rotate(180deg);
  color: var(--brand-secondary);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s ease, padding 0.35s ease;
  padding: 0 22px;
}

.faq-item.open .faq-answer {
  max-height: 600px;
  padding: 0 22px 20px;
}

.faq-answer p {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.75;
}

/* ========== HowTo 步骤 ========== */
.howto-steps {
  display: flex;
  flex-direction: column;
  gap: 0;
  position: relative;
}

.howto-step {
  display: flex;
  gap: 20px;
  padding: 22px 0;
  position: relative;
}

.howto-step:not(:last-child)::after {
  content: "";
  position: absolute;
  left: 19px;
  top: 58px;
  bottom: -14px;
  width: 2px;
  background: var(--border-color);
}

.step-num {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--gradient-1);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.95rem;
  flex-shrink: 0;
  position: relative;
  z-index: 1;
  box-shadow: 0 4px 12px rgba(26, 58, 74, 0.25);
  transition: transform var(--transition), box-shadow var(--transition);
}

.howto-step:hover .step-num {
  transform: scale(1.1);
  box-shadow: 0 6px 18px rgba(26, 58, 74, 0.35);
}

.step-content h4 {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 6px;
  color: var(--text-main);
}

.step-content p {
  font-size: 0.93rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

/* ========== 团队/关于 ========== */
.team-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 24px;
}

.team-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 28px 20px;
  text-align: center;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}

.team-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-md);
  border-color: var(--brand-secondary);
}

.team-avatar {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  margin: 0 auto 14px;
  background: var(--brand-light);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--brand-primary);
  font-size: 1.6rem;
  font-weight: 700;
  transition: transform var(--transition), background var(--transition), color var(--transition);
}

.team-card:hover .team-avatar {
  transform: scale(1.08) rotate(-4deg);
  background: var(--gradient-accent);
  color: var(--brand-dark);
}

.team-card h4 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.team-card .role {
  font-size: 0.85rem;
  color: var(--brand-secondary);
  font-weight: 600;
  margin-bottom: 8px;
}

.team-card p {
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* ========== 联系信息 ========== */
.contact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 24px;
}

.contact-item {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-sm);
  display: flex;
  gap: 16px;
  align-items: flex-start;
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
}

.contact-item:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--brand-secondary);
}

.contact-icon {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-sm);
  background: var(--brand-light);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--brand-primary);
  flex-shrink: 0;
  transition: background var(--transition), color var(--transition);
}

.contact-item:hover .contact-icon {
  background: var(--gradient-accent);
  color: var(--brand-dark);
}

.contact-item h4 {
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.contact-item p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* ========== 页脚 ========== */
.site-footer {
  background: var(--brand-dark);
  color: rgba(255, 255, 255, 0.75);
  padding: 56px 0 0;
  margin-top: 40px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  padding-bottom: 40px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-brand h3 {
  color: #fff;
  font-size: 1.3rem;
  margin-bottom: 12px;
  font-weight: 700;
}

.footer-brand p {
  font-size: 0.88rem;
  line-height: 1.7;
  color: rgba(255, 255, 255, 0.6);
  margin-bottom: 16px;
}

.footer-col h4 {
  color: #fff;
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 16px;
}

.footer-col ul {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-col a {
  color: rgba(255, 255, 255, 0.6);
  font-size: 0.88rem;
  transition: color var(--transition), padding-left var(--transition);
}

.footer-col a:hover {
  color: var(--brand-secondary);
  padding-left: 4px;
}

.footer-bottom {
  padding: 24px 0;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  font-size: 0.82rem;
  color: rgba(255, 255, 255, 0.45);
}

.footer-bottom a {
  color: rgba(255, 255, 255, 0.55);
}

.footer-bottom a:hover {
  color: var(--brand-secondary);
}

/* ========== 返回顶部 ========== */
.back-to-top {
  position: fixed;
  bottom: 28px;
  right: 28px;
  width: 46px;
  height: 46px;
  border-radius: 50%;
  background: var(--brand-primary);
  color: #fff;
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: var(--shadow-md);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: opacity var(--transition), visibility var(--transition), transform var(--transition), background var(--transition);
  z-index: 900;
}

.back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.back-to-top:hover {
  background: var(--brand-secondary);
  color: var(--brand-dark);
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
}

/* ========== 滚动动画 ========== */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ========== 响应式 ========== */
@media (max-width: 1024px) {
  .banner-content h2 {
    font-size: 1.9rem;
  }

  .search-box input {
    width: 110px;
  }
}

@media (max-width: 900px) {
  .main-nav {
    display: none;
  }

  .mobile-menu-btn {
    display: flex;
  }

  .search-box input {
    width: 100px;
  }

  .stats-section {
    grid-template-columns: repeat(2, 1fr);
  }

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

  .banner-content h2 {
    font-size: 1.6rem;
  }

  .banner-content p {
    font-size: 0.95rem;
  }
}

@media (max-width: 600px) {
  .stats-section {
    grid-template-columns: 1fr 1fr;
    gap: 12px;
  }

  .stat-number {
    font-size: 1.8rem;
  }

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

  .article-list {
    grid-template-columns: 1fr;
  }

  .banner-section {
    min-height: 360px;
  }

  .banner-content h2 {
    font-size: 1.35rem;
  }

  .banner-slide {
    padding: 40px 20px;
  }

  .search-box {
    display: none;
  }

  .section-header h2 {
    font-size: 1.4rem;
  }

  .card-grid {
    grid-template-columns: 1fr;
  }

  .team-grid {
    grid-template-columns: 1fr 1fr;
  }

  .contact-grid {
    grid-template-columns: 1fr;
  }

  .howto-step {
    gap: 14px;
  }

  .back-to-top {
    bottom: 18px;
    right: 18px;
    width: 42px;
    height: 42px;
  }
}

@media (max-width: 400px) {
  .team-grid {
    grid-template-columns: 1fr;
  }

  .banner-content h2 {
    font-size: 1.2rem;
  }
}

/* ========== 打印 ========== */
@media print {
  .site-header,
  .back-to-top,
  .banner-dots,
  .theme-toggle,
  .mobile-menu-btn,
  .search-box {
    display: none;
  }

  body {
    padding-top: 0;
  }

  .card,
  .article-card,
  .stat-card {
    box-shadow: none;
    border: 1px solid #ccc;
  }
}

/* ========== 无障碍与偏好 ========== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }

  .reveal {
    opacity: 1;
    transform: none;
  }
}

::selection {
  background: var(--brand-secondary);
  color: var(--brand-dark);
}

:focus-visible {
  outline: 2px solid var(--brand-secondary);
  outline-offset: 2px;
  border-radius: 3px;
}

::-webkit-scrollbar {
  width: 10px;
  height: 10px;
}

::-webkit-scrollbar-track {
  background: var(--bg-alt);
}

::-webkit-scrollbar-thumb {
  background: var(--border-color);
  border-radius: 5px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--text-muted);
}