:root {
  --bg-body: #f5f7fb;
  --bg-card: #ffffff;
  --bg-header: rgba(255, 255, 255, 0.82);
  --bg-glass: rgba(255, 255, 255, 0.65);
  --bg-glass-border: rgba(255, 255, 255, 0.8);
  --text-primary: #1a1a2e;
  --text-secondary: #3d3d5c;
  --text-muted: #6b6b8a;
  --border-light: #e4e8f2;
  --accent: #4a6cf7;
  --accent-hover: #3451d1;
  --accent-light: #eef2ff;
  --accent-glow: rgba(74, 108, 247, 0.28);
  --gradient-1: #4a6cf7;
  --gradient-2: #8b5cf6;
  --gradient-3: #06b6d4;
  --gradient-4: #f472b6;
  --shadow-sm: 0 2px 8px rgba(20, 30, 80, 0.05);
  --shadow-md: 0 10px 30px rgba(20, 30, 80, 0.08);
  --shadow-lg: 0 20px 50px rgba(20, 30, 80, 0.12);
  --radius-sm: 10px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --transition: 0.28s cubic-bezier(0.4, 0, 0.2, 1);
  --font-sans: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --max-width: 1200px;
}

html.dark {
  --bg-body: #0b0b14;
  --bg-card: #16162a;
  --bg-header: rgba(11, 11, 20, 0.82);
  --bg-glass: rgba(22, 22, 42, 0.6);
  --bg-glass-border: rgba(70, 70, 120, 0.4);
  --text-primary: #f0f0fa;
  --text-secondary: #c0c0d8;
  --text-muted: #8888a8;
  --border-light: #262640;
  --accent: #6b8aff;
  --accent-hover: #8aa2ff;
  --accent-light: #1c1c36;
  --accent-glow: rgba(107, 138, 255, 0.3);
  --gradient-1: #6b8aff;
  --gradient-2: #a78bfa;
  --gradient-3: #22d3ee;
  --gradient-4: #f472b6;
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.35);
  --shadow-md: 0 10px 30px rgba(0, 0, 0, 0.45);
  --shadow-lg: 0 20px 50px rgba(0, 0, 0, 0.55);
}

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

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-body);
  color: var(--text-primary);
  line-height: 1.7;
  transition: background-color 0.35s ease, color 0.35s ease;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  top: -30%;
  left: -10%;
  width: 60vw;
  height: 60vw;
  max-width: 700px;
  max-height: 700px;
  background: radial-gradient(circle, var(--accent-glow) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
  z-index: 0;
  opacity: 0.55;
  filter: blur(60px);
}

body::after {
  content: "";
  position: fixed;
  bottom: -25%;
  right: -10%;
  width: 55vw;
  height: 55vw;
  max-width: 650px;
  max-height: 650px;
  background: radial-gradient(circle, rgba(139, 92, 246, 0.22) 0%, transparent 70%);
  border-radius: 50%;
  pointer-events: none;
  z-index: 0;
  opacity: 0.5;
  filter: blur(70px);
}

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

a:hover {
  color: var(--accent-hover);
  text-decoration: underline;
}

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

::selection {
  background: var(--accent);
  color: #fff;
}

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

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

::-webkit-scrollbar-thumb {
  background: linear-gradient(180deg, var(--gradient-1), var(--gradient-2));
  border-radius: 10px;
  border: 2px solid var(--bg-body);
}

::-webkit-scrollbar-thumb:hover {
  background: linear-gradient(180deg, var(--accent-hover), var(--gradient-2));
}

.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
  position: relative;
  z-index: 1;
}

/* ============ 顶部导航 ============ */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: var(--bg-header);
  backdrop-filter: blur(18px) saturate(180%);
  -webkit-backdrop-filter: blur(18px) saturate(180%);
  border-bottom: 1px solid var(--border-light);
  transition: box-shadow 0.35s ease, background 0.35s ease, border-color 0.35s ease;
}

.site-header.scrolled {
  box-shadow: var(--shadow-sm);
  border-bottom-color: transparent;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
  gap: 16px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  font-size: 1.25rem;
  color: var(--text-primary);
  text-decoration: none;
  flex-shrink: 0;
  letter-spacing: -0.01em;
  transition: transform var(--transition);
}

.logo:hover {
  text-decoration: none;
  transform: scale(1.02);
}

.logo svg {
  width: 36px;
  height: 36px;
  filter: drop-shadow(0 4px 10px var(--accent-glow));
}

.logo span {
  white-space: nowrap;
  background: linear-gradient(120deg, var(--gradient-1), var(--gradient-2) 50%, var(--gradient-3));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

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

.main-nav a {
  padding: 8px 14px;
  border-radius: 40px;
  font-size: 0.92rem;
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
  transition: background var(--transition), color var(--transition), transform var(--transition);
  white-space: nowrap;
  position: relative;
}

.main-nav a::after {
  content: "";
  position: absolute;
  bottom: 4px;
  left: 50%;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--gradient-1), var(--gradient-2));
  border-radius: 2px;
  transform: translateX(-50%);
  transition: width var(--transition);
}

.main-nav a:hover {
  background: var(--accent-light);
  color: var(--accent);
  text-decoration: none;
  transform: translateY(-1px);
}

.main-nav a:hover::after {
  width: 40%;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.search-toggle, .theme-toggle, .menu-toggle {
  background: var(--bg-glass);
  border: 1px solid var(--border-light);
  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), border var(--transition), color var(--transition), transform var(--transition), box-shadow var(--transition);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.search-toggle:hover, .theme-toggle:hover, .menu-toggle:hover {
  background: var(--accent-light);
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-2px);
  box-shadow: 0 6px 16px var(--accent-glow);
}

.search-toggle:active, .theme-toggle:active, .menu-toggle:active {
  transform: translateY(0) scale(0.95);
}

.menu-toggle {
  display: none;
}

/* ============ 搜索面板 ============ */
.search-panel {
  display: none;
  padding: 12px 0 18px;
  border-top: 1px solid var(--border-light);
  animation: slideDown 0.3s ease;
}

.search-panel.active {
  display: block;
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.search-form {
  display: flex;
  gap: 8px;
  max-width: 600px;
  margin: 0 auto;
}

.search-form input {
  flex: 1;
  padding: 12px 20px;
  border-radius: 40px;
  border: 1px solid var(--border-light);
  background: var(--bg-card);
  color: var(--text-primary);
  font-size: 1rem;
  font-family: inherit;
  outline: none;
  transition: border var(--transition), box-shadow var(--transition), background var(--transition);
}

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

.search-form input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px var(--accent-glow);
  background: var(--bg-card);
}

.search-form button {
  padding: 12px 28px;
  border-radius: 40px;
  border: none;
  background: linear-gradient(135deg, var(--gradient-1), var(--gradient-2));
  color: #fff;
  font-weight: 600;
  font-size: 0.98rem;
  font-family: inherit;
  cursor: pointer;
  transition: transform var(--transition), box-shadow var(--transition), filter var(--transition);
  white-space: nowrap;
  box-shadow: 0 6px 18px var(--accent-glow);
}

.search-form button:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 26px var(--accent-glow);
  filter: brightness(1.06);
}

.search-form button:active {
  transform: translateY(0) scale(0.98);
}

/* ============ 移动菜单 ============ */
.mobile-nav {
  display: none;
  flex-direction: column;
  background: var(--bg-card);
  border-top: 1px solid var(--border-light);
  padding: 12px 20px 20px;
  gap: 4px;
  animation: slideDown 0.3s ease;
}

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

.mobile-nav a {
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 1rem;
  font-weight: 500;
  transition: background var(--transition), color var(--transition), transform var(--transition);
}

.mobile-nav a:hover {
  background: var(--accent-light);
  color: var(--accent);
  text-decoration: none;
  transform: translateX(4px);
}

/* ============ 面包屑 ============ */
.breadcrumb {
  padding: 18px 0 8px;
  font-size: 0.88rem;
  color: var(--text-muted);
}

.breadcrumb ol {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  align-items: center;
}

.breadcrumb li + li::before {
  content: "›";
  margin-right: 6px;
  color: var(--text-muted);
  opacity: 0.7;
}

.breadcrumb a {
  color: var(--text-muted);
  text-decoration: none;
  transition: color var(--transition);
}

.breadcrumb a:hover {
  color: var(--accent);
  text-decoration: none;
}

/* ============ 主内容区 ============ */
main {
  padding-bottom: 60px;
}

section {
  margin-bottom: 60px;
}

/* ============ Hero 渐变 Banner ============ */
.hero {
  position: relative;
  padding: 64px 36px 56px;
  margin-top: 16px;
  text-align: center;
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: linear-gradient(135deg, rgba(74, 108, 247, 0.14) 0%, rgba(139, 92, 246, 0.14) 45%, rgba(6, 182, 212, 0.12) 100%);
  border: 1px solid var(--bg-glass-border);
  box-shadow: var(--shadow-md);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  isolation: isolate;
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 15% 20%, rgba(74, 108, 247, 0.28) 0%, transparent 45%),
    radial-gradient(circle at 85% 15%, rgba(139, 92, 246, 0.24) 0%, transparent 45%),
    radial-gradient(circle at 50% 100%, rgba(6, 182, 212, 0.2) 0%, transparent 55%);
  z-index: -1;
  animation: heroGlow 12s ease-in-out infinite alternate;
}

.hero::after {
  content: "";
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: conic-gradient(from 0deg, transparent 0deg, rgba(255, 255, 255, 0.06) 60deg, transparent 120deg);
  animation: heroRotate 24s linear infinite;
  z-index: -1;
  pointer-events: none;
}

@keyframes heroGlow {
  0% {
    opacity: 0.85;
    transform: scale(1);
  }
  100% {
    opacity: 1;
    transform: scale(1.05);
  }
}

@keyframes heroRotate {
  from {
    transform: rotate(0deg);
  }
  to {
    transform: rotate(360deg);
  }
}

.hero h1 {
  font-size: clamp(1.75rem, 5vw, 2.9rem);
  font-weight: 800;
  line-height: 1.25;
  margin-bottom: 18px;
  letter-spacing: -0.02em;
  animation: fadeUp 0.7s ease both;
}

.hero h1 .highlight {
  position: relative;
  background: linear-gradient(120deg, var(--gradient-1), var(--gradient-2) 50%, var(--gradient-3));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  display: inline-block;
}

.hero h1 .highlight::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -4px;
  width: 100%;
  height: 6px;
  border-radius: 6px;
  background: linear-gradient(90deg, var(--gradient-1), var(--gradient-2), var(--gradient-3));
  opacity: 0.35;
  filter: blur(2px);
}

.hero-sub {
  font-size: 1.08rem;
  color: var(--text-secondary);
  max-width: 720px;
  margin: 0 auto 32px;
  line-height: 1.85;
  animation: fadeUp 0.7s ease 0.1s both;
}

.hero-cta {
  display: flex;
  gap: 14px;
  justify-content: center;
  flex-wrap: wrap;
  animation: fadeUp 0.7s ease 0.2s both;
}

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

/* ============ 按钮 ============ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 13px 30px;
  border-radius: 40px;
  font-weight: 600;
  font-size: 1rem;
  font-family: inherit;
  text-decoration: none;
  transition: all var(--transition);
  cursor: pointer;
  border: none;
  position: relative;
  overflow: hidden;
}

.btn-primary {
  background: linear-gradient(135deg, var(--gradient-1), var(--gradient-2));
  color: #fff;
  box-shadow: 0 8px 22px var(--accent-glow);
}

.btn-primary::before {
  content: "";
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.25), transparent);
  transition: left 0.6s ease;
}

.btn-primary:hover {
  color: #fff;
  text-decoration: none;
  transform: translateY(-3px);
  box-shadow: 0 14px 32px var(--accent-glow);
  filter: brightness(1.05);
}

.btn-primary:hover::before {
  left: 100%;
}

.btn-outline {
  background: var(--bg-glass);
  color: var(--text-primary);
  border: 1.5px solid var(--border-light);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
}

.btn-outline:hover {
  border-color: var(--accent);
  color: var(--accent);
  text-decoration: none;
  transform: translateY(-3px);
  background: var(--accent-light);
  box-shadow: 0 10px 24px var(--accent-glow);
}

.btn:active {
  transform: translateY(-1px) scale(0.98);
}

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

.card {
  background: var(--bg-card);
  border-radius: var(--radius-md);
  padding: 30px 26px;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border-light);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  position: relative;
  overflow: hidden;
}

.card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: linear-gradient(90deg, var(--gradient-1), var(--gradient-2), var(--gradient-3));
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.4s ease;
}

.card:hover {
  transform: translateY(-6px);
  box-shadow: var(--shadow-lg);
  border-color: transparent;
}

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

.card-icon {
  width: 48px;
  height: 48px;
  margin-bottom: 18px;
  transition: transform var(--transition);
}

.card:hover .card-icon {
  transform: scale(1.1) rotate(-4deg);
}

.card h3 {
  font-size: 1.15rem;
  margin-bottom: 10px;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -0.01em;
}

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

/* ============ 章节标题 ============ */
.section-title {
  font-size: 1.65rem;
  font-weight: 800;
  margin-bottom: 10px;
  letter-spacing: -0.015em;
  position: relative;
  display: inline-block;
}

.section-title::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -6px;
  width: 48px;
  height: 4px;
  border-radius: 4px;
  background: linear-gradient(90deg, var(--gradient-1), var(--gradient-2));
}

.section-desc {
  color: var(--text-muted);
  font-size: 0.98rem;
  margin-bottom: 34px;
  max-width: 720px;
  margin-top: 14px;
}

/* ============ 文章列表 ============ */
.article-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 22px;
}

.article-item {
  background: var(--bg-card);
  border-radius: var(--radius-md);
  padding: 26px 24px;
  border: 1px solid var(--border-light);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  display: flex;
  flex-direction: column;
  position: relative;
  overflow: hidden;
}

.article-item::after {
  content: "";
  position: absolute;
  bottom: 0;
  right: 0;
  width: 80px;
  height: 80px;
  background: radial-gradient(circle, var(--accent-glow) 0%, transparent 70%);
  opacity: 0;
  transition: opacity var(--transition);
  pointer-events: none;
}

.article-item:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-md);
  border-color: var(--accent);
}

.article-item:hover::after {
  opacity: 1;
}

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

.article-meta span {
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.article-meta span:first-child {
  color: var(--accent);
  font-weight: 600;
}

.article-item h3 {
  font-size: 1.08rem;
  margin-bottom: 10px;
  font-weight: 700;
  line-height: 1.45;
}

.article-item h3 a {
  color: var(--text-primary);
  text-decoration: none;
  transition: color var(--transition);
}

.article-item h3 a:hover {
  color: var(--accent);
  text-decoration: none;
}

.article-item p {
  color: var(--text-secondary);
  font-size: 0.92rem;
  line-height: 1.75;
  flex: 1;
  margin-bottom: 16px;
}

.read-more {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--accent);
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  transition: gap var(--transition), color var(--transition);
  align-self: flex-start;
}

.read-more:hover {
  text-decoration: none;
  gap: 8px;
  color: var(--accent-hover);
}

/* ============ FAQ ============ */
.faq-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

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

.faq-item:hover {
  border-color: var(--accent);
}

.faq-item.open {
  border-color: var(--accent);
  box-shadow: 0 8px 24px var(--accent-glow);
}

.faq-question {
  width: 100%;
  padding: 18px 22px;
  background: none;
  border: none;
  text-align: left;
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-primary);
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
  transition: background var(--transition), color var(--transition);
  font-family: inherit;
  line-height: 1.5;
}

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

.faq-question .icon {
  flex-shrink: 0;
  width: 20px;
  height: 20px;
  transition: transform 0.35s ease, color var(--transition);
  color: var(--accent);
}

.faq-item.open .faq-question .icon {
  transform: rotate(180deg);
}

.faq-item.open .faq-question {
  color: var(--accent);
}

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease, padding 0.4s ease;
  padding: 0 22px;
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.85;
}

.faq-item.open .faq-answer {
  max-height: 700px;
  padding: 0 22px 22px;
}

/* ============ HowTo 步骤 ============ */
.howto-steps {
  display: flex;
  flex-direction: column;
  gap: 20px;
  counter-reset: step;
}

.howto-step {
  display: flex;
  gap: 18px;
  background: var(--bg-card);
  padding: 24px 26px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-light);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  position: relative;
  overflow: hidden;
}

.howto-step::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 4px;
  height: 100%;
  background: linear-gradient(180deg, var(--gradient-1), var(--gradient-2));
  transform: scaleY(0);
  transform-origin: top;
  transition: transform 0.4s ease;
}

.howto-step:hover {
  transform: translateX(6px);
  box-shadow: var(--shadow-md);
  border-color: transparent;
}

.howto-step:hover::before {
  transform: scaleY(1);
}

.step-number {
  flex-shrink: 0;
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--gradient-1), var(--gradient-2));
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.1rem;
  box-shadow: 0 6px 16px var(--accent-glow);
  transition: transform var(--transition);
}

.howto-step:hover .step-number {
  transform: scale(1.1) rotate(-6deg);
}

.step-content h3 {
  font-size: 1.05rem;
  margin-bottom: 6px;
  font-weight: 700;
  color: var(--text-primary);
}

.step-content p {
  color: var(--text-secondary);
  font-size: 0.94rem;
  line-height: 1.75;
}

/* ============ 数字统计 ============ */
.stats-row {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  gap: 20px;
  margin-top: 32px;
}

.stat-item {
  background: var(--bg-card);
  border-radius: var(--radius-md);
  padding: 30px 20px;
  text-align: center;
  border: 1px solid var(--border-light);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition), border-color var(--transition);
  position: relative;
  overflow: hidden;
}

.stat-item::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, rgba(74, 108, 247, 0.06), rgba(139, 92, 246, 0.06));
  opacity: 0;
  transition: opacity var(--transition);
}

.stat-item:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-md);
  border-color: var(--accent);
}

.stat-item:hover::before {
  opacity: 1;
}

.stat-number {
  font-size: 2.3rem;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 8px;
  background: linear-gradient(135deg, var(--gradient-1), var(--gradient-2));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  position: relative;
}

.stat-label {
  color: var(--text-muted);
  font-size: 0.9rem;
  position: relative;
}

/* ============ 联系信息 ============ */
.contact-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 20px;
}

.contact-item {
  display: flex;
  gap: 14px;
  align-items: flex-start;
  background: var(--bg-card);
  padding: 24px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-light);
  box-shadow: var(--shadow-sm);
  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(--accent);
}

.contact-item svg {
  flex-shrink: 0;
  width: 24px;
  height: 24px;
  color: var(--accent);
  margin-top: 2px;
  transition: transform var(--transition);
}

.contact-item:hover svg {
  transform: scale(1.15);
}

.contact-item h4 {
  font-size: 0.95rem;
  margin-bottom: 4px;
  font-weight: 700;
  color: var(--text-primary);
}

.contact-item p {
  color: var(--text-secondary);
  font-size: 0.9rem;
  line-height: 1.65;
}

/* ============ 页脚 ============ */
.site-footer {
  background: var(--bg-card);
  border-top: 1px solid var(--border-light);
  padding: 52px 0 28px;
  color: var(--text-secondary);
  font-size: 0.9rem;
  position: relative;
  z-index: 1;
}

.site-footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: linear-gradient(90deg, var(--gradient-1), var(--gradient-2), var(--gradient-3), var(--gradient-4));
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 32px;
  margin-bottom: 40px;
}

.footer-col h4 {
  font-size: 1rem;
  margin-bottom: 16px;
  color: var(--text-primary);
  font-weight: 700;
  position: relative;
  padding-bottom: 10px;
}

.footer-col h4::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: 0;
  width: 28px;
  height: 3px;
  border-radius: 3px;
  background: linear-gradient(90deg, var(--gradient-1), var(--gradient-2));
}

.footer-col ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 9px;
}

.footer-col a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.88rem;
  transition: color var(--transition), padding-left var(--transition);
  display: inline-block;
}

.footer-col a:hover {
  color: var(--accent);
  text-decoration: none;
  padding-left: 4px;
}

.footer-bottom {
  border-top: 1px solid var(--border-light);
  padding-top: 24px;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 12px;
  color: var(--text-muted);
  font-size: 0.85rem;
}

.footer-bottom a {
  color: var(--text-muted);
  transition: color var(--transition);
}

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

/* ============ 返回顶部 ============ */
.back-to-top {
  position: fixed;
  bottom: 28px;
  right: 28px;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--gradient-1), var(--gradient-2));
  color: #fff;
  border: none;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: 0 8px 24px var(--accent-glow);
  opacity: 0;
  visibility: hidden;
  transform: translateY(16px) scale(0.9);
  transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  z-index: 999;
}

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

.back-to-top:hover {
  transform: translateY(-4px) scale(1.06);
  box-shadow: 0 14px 32px var(--accent-glow);
  filter: brightness(1.08);
}

.back-to-top:active {
  transform: translateY(-1px) scale(0.98);
}

/* ============ 滚动动画 ============ */
.reveal {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 0.7s cubic-bezier(0.4, 0, 0.2, 1), transform 0.7s cubic-bezier(0.4, 0, 0.2, 1);
  will-change: opacity, transform;
}

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

/* ============ 无障碍隐藏 ============ */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ============ 响应式 ============ */
@media (max-width: 900px) {
  .main-nav {
    display: none;
  }

  .menu-toggle {
    display: flex;
  }

  .hero {
    padding: 48px 24px 42px;
  }

  section {
    margin-bottom: 48px;
  }

  .section-title {
    font-size: 1.45rem;
  }
}

@media (max-width: 600px) {
  .container {
    padding: 0 16px;
  }

  .header-inner {
    height: 60px;
  }

  .logo span {
    font-size: 1rem;
  }

  .logo svg {
    width: 30px;
    height: 30px;
  }

  .search-toggle, .theme-toggle, .menu-toggle {
    width: 36px;
    height: 36px;
  }

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

  .hero {
    padding: 40px 18px 36px;
    border-radius: var(--radius-md);
  }

  .hero h1 {
    font-size: 1.6rem;
  }

  .hero-sub {
    font-size: 0.98rem;
  }

  .hero-cta {
    flex-direction: column;
    align-items: stretch;
  }

  .btn {
    width: 100%;
  }

  .search-form {
    flex-direction: column;
  }

  .search-form button {
    width: 100%;
  }

  .howto-step {
    flex-direction: column;
    gap: 12px;
    padding: 20px;
  }

  .howto-step:hover {
    transform: translateY(-3px);
  }

  .step-number {
    width: 38px;
    height: 38px;
    font-size: 1rem;
  }

  .stat-number {
    font-size: 1.9rem;
  }

  .back-to-top {
    bottom: 18px;
    right: 18px;
    width: 44px;
    height: 44px;
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}

@media (max-width: 380px) {
  .logo span {
    display: none;
  }

  .hero h1 {
    font-size: 1.4rem;
  }
}

/* ============ 减少动画偏好 ============ */
@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;
  }
}

/* ============ 打印样式 ============ */
@media print {
  .site-header,
  .back-to-top,
  .hero-cta,
  .search-panel,
  .mobile-nav {
    display: none !important;
  }

  body {
    background: #fff;
    color: #000;
  }

  .card, .article-item, .faq-item, .howto-step {
    box-shadow: none;
    border: 1px solid #ccc;
  }
}