```css
/* ============================================
   汗汗漫画网 - 全局样式表
   风格：现代科技感 + 柔和渐变 + 毛玻璃质感
   设计原则：清晰层级、舒适留白、流畅动效
   ============================================ */

/* ---------- CSS 变量与主题系统 ---------- */
:root {
  /* 主色板 - 科技蓝紫渐变 */
  --primary-300: #93C5FD;
  --primary-400: #60A5FA;
  --primary-500: #3B82F6;
  --primary-600: #2563EB;
  --primary-700: #1D4ED8;

  --accent-300: #C4B5FD;
  --accent-400: #A78BFA;
  --accent-500: #8B5CF6;

  --bg-body: #F4F7FE;
  --bg-card: #FFFFFF;
  --bg-nav: rgba(255, 255, 255, 0.82);
  --bg-footer: #131B2E;
  --bg-hero-glow: rgba(99, 102, 241, 0.08);

  --text-primary: #1E293B;
  --text-secondary: #475569;
  --text-heading: #0F172A;
  --text-link: #1D4ED8;
  --text-footer: #B0C4DE;
  --text-muted: #64748B;

  --border-light: rgba(148, 163, 184, 0.25);
  --border-focus: rgba(59, 130, 246, 0.5);

  --btn-bg: linear-gradient(135deg, var(--primary-500), var(--accent-500));
  --btn-text: #FFFFFF;
  --btn-shadow: 0 8px 20px rgba(59, 130, 246, 0.3);

  --card-shadow: 0 4px 16px rgba(15, 23, 42, 0.06);
  --card-shadow-hover: 0 12px 32px rgba(15, 23, 42, 0.12);

  --glass-bg: rgba(255, 255, 255, 0.65);
  --glass-border: rgba(255, 255, 255, 0.3);
  --glass-blur: 16px;

  --radius-sm: 10px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --radius-full: 999px;

  --transition-fast: 0.2s ease;
  --transition-base: 0.3s ease;
  --transition-slow: 0.5s ease;

  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
}

/* 暗黑模式 - 基于系统偏好 */
@media (prefers-color-scheme: dark) {
  :root {
    --bg-body: #0B1220;
    --bg-card: #151E31;
    --bg-nav: rgba(21, 30, 49, 0.85);
    --bg-footer: #070C18;
    --bg-hero-glow: rgba(139, 92, 246, 0.12);

    --text-primary: #D7E1F0;
    --text-secondary: #9DB2D0;
    --text-heading: #EDF2F9;
    --text-link: #93C5FD;
    --text-footer: #8BA3C7;
    --text-muted: #7A8FB0;

    --border-light: rgba(148, 163, 184, 0.18);
    --border-focus: rgba(96, 165, 250, 0.7);

    --btn-bg: linear-gradient(135deg, #3B82F6, #8B5CF6);
    --btn-shadow: 0 8px 24px rgba(59, 130, 246, 0.25);

    --card-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
    --card-shadow-hover: 0 12px 36px rgba(0, 0, 0, 0.5);

    --glass-bg: rgba(21, 30, 49, 0.6);
    --glass-border: rgba(148, 163, 184, 0.15);
  }
}

/* 手动暗黑模式类（JS切换用） */
html.dark {
  --bg-body: #0B1220;
  --bg-card: #151E31;
  --bg-nav: rgba(21, 30, 49, 0.85);
  --bg-footer: #070C18;
  --bg-hero-glow: rgba(139, 92, 246, 0.12);

  --text-primary: #D7E1F0;
  --text-secondary: #9DB2D0;
  --text-heading: #EDF2F9;
  --text-link: #93C5FD;
  --text-footer: #8BA3C7;
  --text-muted: #7A8FB0;

  --border-light: rgba(148, 163, 184, 0.18);
  --border-focus: rgba(96, 165, 250, 0.7);

  --btn-bg: linear-gradient(135deg, #3B82F6, #8B5CF6);
  --btn-shadow: 0 8px 24px rgba(59, 130, 246, 0.25);

  --card-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
  --card-shadow-hover: 0 12px 36px rgba(0, 0, 0, 0.5);

  --glass-bg: rgba(21, 30, 49, 0.6);
  --glass-border: rgba(148, 163, 184, 0.15);
}

/* ---------- 全局重置 ---------- */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

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

body {
  background: var(--bg-body);
  color: var(--text-primary);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  min-height: 100vh;
  transition: background-color var(--transition-base),
    color var(--transition-base);
  overflow-x: hidden;
}

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

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

a:hover {
  color: var(--primary-400);
}

ul,
ol {
  list-style: none;
}

button {
  font-family: inherit;
  border: none;
  background: none;
  cursor: pointer;
  color: inherit;
}

input {
  font-family: inherit;
}

/* ---------- 工具类 ---------- */
.container {
  width: 100%;
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 48px 0;
}

.section-title {
  font-size: 2rem;
  font-weight: 800;
  color: var(--text-heading);
  margin-bottom: 32px;
  letter-spacing: -0.02em;
  position: relative;
  display: inline-block;
}

.section-title::after {
  content: "";
  position: absolute;
  bottom: -8px;
  left: 0;
  width: 56px;
  height: 4px;
  background: linear-gradient(90deg, var(--primary-500), var(--accent-500));
  border-radius: var(--radius-full);
}

/* ---------- 卡片通用样式 ---------- */
.card {
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  padding: 28px 24px;
  border: 1px solid var(--border-light);
  box-shadow: var(--card-shadow);
  transition: transform var(--transition-base),
    box-shadow var(--transition-base),
    background-color var(--transition-base),
    border-color var(--transition-base);
  position: relative;
  overflow: hidden;
}

.card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--primary-500), var(--accent-500));
  opacity: 0;
  transition: opacity var(--transition-base);
}

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

.card:hover::before {
  opacity: 1;
}

.card h3 {
  color: var(--text-heading);
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 12px;
  letter-spacing: -0.01em;
}

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

.card .meta {
  margin-top: 16px;
  color: var(--text-link);
  font-weight: 600;
  font-size: 0.9rem;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

/* ---------- 毛玻璃效果通用 ---------- */
.glass {
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
}

/* ---------- 导航栏 ---------- */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg-nav);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border-light);
  transition: background-color var(--transition-base),
    border-color var(--transition-base);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
  gap: 24px;
}

.logo a {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--text-heading);
  letter-spacing: -0.02em;
  background: linear-gradient(135deg, var(--primary-600), var(--accent-500));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  white-space: nowrap;
}

.logo span {
  font-weight: 300;
}

.nav-links {
  display: flex;
  gap: 32px;
  align-items: center;
}

.nav-links a {
  color: var(--text-secondary);
  font-weight: 500;
  font-size: 0.95rem;
  padding: 8px 4px;
  border-bottom: 2px solid transparent;
  transition: color var(--transition-fast),
    border-color var(--transition-fast);
  position: relative;
}

.nav-links a::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--primary-500), var(--accent-500));
  transition: width var(--transition-base);
}

.nav-links a:hover {
  color: var(--text-heading);
}

.nav-links a:hover::after {
  width: 100%;
}

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

.search-box {
  display: flex;
  align-items: center;
  background: var(--bg-body);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-full);
  padding: 4px 8px 4px 16px;
  transition: border-color var(--transition-fast),
    box-shadow var(--transition-fast);
}

.search-box:focus-within {
  border-color: var(--primary-500);
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.1);
}

.search-box input {
  border: none;
  background: transparent;
  color: var(--text-primary);
  padding: 8px 10px;
  font-size: 0.9rem;
  outline: none;
  width: 160px;
  transition: width var(--transition-base);
}

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

.search-box button {
  background: transparent;
  border: none;
  color: var(--text-secondary);
  cursor: pointer;
  font-size: 1.1rem;
  padding: 6px 10px;
  border-radius: var(--radius-full);
  transition: color var(--transition-fast),
    background-color var(--transition-fast);
}

.search-box button:hover {
  color: var(--primary-500);
  background: rgba(59, 130, 246, 0.1);
}

.theme-toggle,
.menu-toggle {
  background: var(--bg-body);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  padding: 8px 12px;
  color: var(--text-primary);
  font-size: 1rem;
  cursor: pointer;
  transition: all var(--transition-fast);
  display: flex;
  align-items: center;
  justify-content: center;
}

.theme-toggle:hover,
.menu-toggle:hover {
  border-color: var(--primary-500);
  background: rgba(59, 130, 246, 0.08);
}

.menu-toggle {
  display: none;
}

/* 移动端菜单 */
.mobile-menu {
  display: none;
  flex-direction: column;
  background: var(--bg-nav);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  padding: 12px 0;
  border-top: 1px solid var(--border-light);
  animation: slideDown 0.3s ease;
}

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

.mobile-menu a {
  padding: 12px 24px;
  color: var(--text-primary);
  font-weight: 500;
  border-left: 3px solid transparent;
  transition: all var(--transition-fast);
}

.mobile-menu a:hover {
  background: rgba(59, 130, 246, 0.08);
  border-left-color: var(--primary-500);
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ---------- 面包屑 ---------- */
.breadcrumb {
  padding: 20px 0 0;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.breadcrumb a {
  color: var(--text-link);
  font-weight: 500;
}

.breadcrumb a:hover {
  text-decoration: underline;
}

/* ---------- Hero 主视觉 ---------- */
.hero {
  padding: 64px 0 48px;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  top: -50%;
  right: -20%;
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, var(--bg-hero-glow), transparent 70%);
  border-radius: 50%;
  pointer-events: none;
}

.hero::after {
  content: "";
  position: absolute;
  bottom: -30%;
  left: -10%;
  width: 400px;
  height: 400px;
  background: radial-gradient(circle, rgba(139, 92, 246, 0.06), transparent 70%);
  border-radius: 50%;
  pointer-events: none;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 48px;
  align-items: center;
  position: relative;
  z-index: 1;
}

.hero h1 {
  font-size: 3rem;
  font-weight: 800;
  color: var(--text-heading);
  line-height: 1.2;
  margin-bottom: 20px;
  letter-spacing: -0.03em;
}

.hero h1 span {
  background: linear-gradient(135deg, var(--primary-500), var(--accent-500));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero p {
  font-size: 1.1rem;
  color: var(--text-secondary);
  margin-bottom: 28px;
  max-width: 600px;
  line-height: 1.8;
}

.hero-cta {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background: var(--btn-bg);
  color: var(--btn-text);
  padding: 14px 32px;
  border-radius: var(--radius-full);
  font-weight: 600;
  font-size: 1rem;
  text-decoration: none;
  transition: all var(--transition-base);
  border: none;
  cursor: pointer;
  box-shadow: var(--btn-shadow);
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: "";
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
  transition: left 0.5s ease;
}

.btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 12px 28px rgba(59, 130, 246, 0.4);
}

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

.btn-outline {
  background: transparent;
  border: 2px solid var(--primary-500);
  color: var(--primary-500);
  box-shadow: none;
}

.btn-outline:hover {
  background: var(--primary-500);
  color: #fff;
  box-shadow: var(--btn-shadow);
}

.hero-card {
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--card-shadow);
  transform: rotate(1deg);
  transition: transform var(--transition-base);
}

.hero-card:hover {
  transform: rotate(0deg) scale(1.02);
}

.hero-card svg {
  width: 100%;
  height: auto;
  border-radius: var(--radius-md);
}

/* ---------- 品牌介绍 ---------- */
.brand-box {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  background: var(--bg-card);
  padding: 40px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-light);
  box-shadow: var(--card-shadow);
  transition: background-color var(--transition-base),
    border-color var(--transition-base);
}

.brand-box h3 {
  color: var(--text-heading);
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 16px;
  position: relative;
  padding-bottom: 12px;
}

.brand-box h3::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 40px;
  height: 3px;
  background: linear-gradient(90deg, var(--primary-500), var(--accent-500));
  border-radius: var(--radius-full);
}

.brand-box p {
  color: var(--text-primary);
  line-height: 1.8;
}

.brand-box ul {
  color: var(--text-primary);
  line-height: 2;
}

.brand-box ul li {
  padding-left: 20px;
  position: relative;
}

.brand-box ul li::before {
  content: "✦";
  position: absolute;
  left: 0;
  color: var(--accent-500);
  font-size: 0.8rem;
}

/* ---------- 分类卡片 ---------- */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 24px;
}

/* ---------- 解决方案 ---------- */
.solution-grid {
  display: flex;
  gap: 24px;
  flex-wrap: wrap;
}

.solution-item {
  flex: 1;
  min-width: 200px;
  background: var(--bg-card);
  padding: 28px 24px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-light);
  box-shadow: var(--card-shadow);
  transition: all var(--transition-base);
  position: relative;
  overflow: hidden;
}

.solution-item::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.05), rgba(139, 92, 246, 0.05));
  opacity: 0;
  transition: opacity var(--transition-base);
}

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

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

.solution-item h3 {
  color: var(--text-heading);
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 12px;
  position: relative;
}

.solution-item p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  position: relative;
}

/* ---------- 文章列表 ---------- */
.article-list {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 32px;
}

.article-item {
  border-bottom: 1px solid var(--border-light);
  padding-bottom: 24px;
  transition: border-color var(--transition-fast);
  position: relative;
  padding-left: 16px;
}

.article-item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 8px;
  width: 4px;
  height: 40px;
  background: linear-gradient(180deg, var(--primary-500), var(--accent-500));
  border-radius: var(--radius-full);
  opacity: 0.6;
  transition: opacity var(--transition-fast);
}

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

.article-item h4 {
  font-size: 1.15rem;
  color: var(--text-heading);
  margin-bottom: 8px;
  font-weight: 600;
  transition: color var(--transition-fast);
}

.article-item:hover h4 {
  color: var(--primary-500);
}

.article-item .date {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 8px;
  display: block;
}

.article-item p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-bottom: 8px;
  line-height: 1.7;
}

.article-item a {
  color: var(--text-link);
  font-weight: 500;
  font-size: 0.9rem;
  display: inline-flex;
  align-items: center;
  gap: 4px;
  transition: gap var(--transition-fast);
}

.article-item a:hover {
  gap: 8px;
}

/* ---------- FAQ ---------- */
.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: 20px 24px;
  margin-bottom: 16px;
  transition: all var(--transition-base);
  box-shadow: var(--card-shadow);
}

.faq-item:hover {
  border-color: var(--border-focus);
  box-shadow: var(--card-shadow-hover);
}

.faq-question {
  font-weight: 600;
  color: var(--text-heading);
  font-size: 1.05rem;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
}

.faq-question span {
  font-size: 1.6rem;
  font-weight: 300;
  color: var(--primary-500);
  transition: transform var(--transition-base);
  line-height: 1;
}

.faq-question span.rotate {
  transform: rotate(45deg);
}

.faq-answer {
  margin-top: 16px;
  color: var(--text-primary);
  line-height: 1.8;
  padding-top: 16px;
  border-top: 1px solid var(--border-light);
  animation: fadeIn 0.3s ease;
}

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

/* ---------- HowTo 教程 ---------- */
.howto-box {
  background: var(--bg-card);
  padding: 32px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-light);
  box-shadow: var(--card-shadow);
  color: var(--text-primary);
  line-height: 1.9;
}

.howto-box h3 {
  color: var(--text-heading);
  font-size: 1.3rem;
  margin-bottom: 16px;
  font-weight: 700;
}

.howto-box p {
  margin-bottom: 12px;
}

.howto-box strong {
  color: var(--text-heading);
}

.howto-box .step {
  background: rgba(59, 130, 246, 0.06);
  border-left: 3px solid var(--primary-500);
  padding: 12px 16px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin-bottom: 12px;
}

/* ---------- 友情链接 ---------- */
.friend-links {
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 20px;
  border-top: 1px solid var(--border-light);
  padding-top: 24px;
  margin-top: 48px;
}

.friend-links a {
  color: var(--text-link);
  font-weight: 500;
  margin: 0 8px;
  transition: color var(--transition-fast);
}

.friend-links a:hover {
  color: var(--primary-400);
  text-decoration: underline;
}

/* ---------- 表格 ---------- */
.info-table {
  width: 100%;
  border-collapse: collapse;
  background: var(--bg-card);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--card-shadow);
  transition: background-color var(--transition-base);
}

.info-table th,
.info-table td {
  padding: 14px 16px;
  text-align: left;
  border-bottom: 1px solid var(--border-light);
}

.info-table th {
  background: var(--bg-nav);
  color: var(--text-heading);
  font-weight: 600;
  font-size: 0.95rem;
}

.info-table td {
  color: var(--text-primary);
}

.info-table tr:last-child td {
  border-bottom: none;
}

.info-table tr:hover td {
  background: rgba(59, 130, 246, 0.04);
}

/* ---------- 页脚 ---------- */
.footer {
  background: var(--bg-footer);
  color: var(--text-footer);
  padding: 48px 0 24px;
  margin-top: 64px;
  position: relative;
}

.footer::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, rgba(139, 92, 246, 0.4), transparent);
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 40px;
  margin-bottom: 40px;
}

.footer h4 {
  color: #FFFFFF;
  margin-bottom: 20px;
  font-size: 1.1rem;
  font-weight: 600;
  position: relative;
  padding-bottom: 10px;
}

.footer h4::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0;
  width: 30px;
  height: 2px;
  background: linear-gradient(90deg, var(--primary-500), var(--accent-500));
  border-radius: var(--radius-full);
}

.footer a {
  color: var(--text-footer);
  text-decoration: none;
  display: block;
  margin-bottom: 10px;
  font-size: 0.9rem;
  transition: all var(--transition-fast);
  position: relative;
  padding-left: 0;
}

.footer a:hover {
  color: #FFFFFF;
  padding-left: 8px;
  text-decoration: none;
}

.footer p {
  color: var(--text-footer);
  font-size: 0.9rem;
  line-height: 1.8;
}

.footer-bottom {
  border-top: 1px solid rgba(148, 163, 184, 0.15);
  padding-top: 24px;
  text-align: center;
  font-size: 0.85rem;
  color: #8BA3C7;
}

/* ---------- 返回顶部 ---------- */
.back-to-top {
  position: fixed;
  bottom: 28px;
  right: 28px;
  background: var(--btn-bg);
  color: white;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  border: none;
  font-size: 1.4rem;
  cursor: pointer;
  box-shadow: var(--btn-shadow);
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition-base);
  opacity: 0;
  visibility: hidden;
  transform: translateY(20px);
}

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

.back-to-top:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 32px rgba(59, 130, 246, 0.4);
}

/* ---------- 滚动动画 ---------- */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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

/* ---------- 响应式设计 ---------- */
@media (max-width: 1024px) {
  .hero h1 {
    font-size: 2.4rem;
  }

  .hero-grid {
    gap: 32px;
  }

  .brand-box {
    grid-template-columns: 1fr;
    gap: 24px;
  }
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
  }

  .menu-toggle {
    display: flex;
  }

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

  .hero {
    padding: 40px 0 32px;
  }

  .hero-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .hero p {
    font-size: 1rem;
  }

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

  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 32px;
  }

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

  .section {
    padding: 32px 0;
  }

  .section-title {
    font-size: 1.6rem;
  }

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

  .solution-grid {
    flex-direction: column;
  }

  .solution-item {
    min-width: 100%;
  }

  .container {
    padding: 0 16px;
  }

  .brand-box {
    padding: 24px;
  }

  .howto-box {
    padding: 24px;
  }

  .back-to-top {
    bottom: 20px;
    right: 20px;
    width: 42px;
    height: 42px;
    font-size: 1.2rem;
  }
}

@media (max-width: 480px) {
  .nav-inner {
    height: 64px;
  }

  .logo a {
    font-size: 1.3rem;
  }

  .search-box input {
    width: 80px;
    font-size: 0.85rem;
  }

  .hero h1 {
    font-size: 1.7rem;
  }

  .hero-cta {
    flex-direction: column;
  }

  .btn {
    width: 100%;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .faq-item {
    padding: 16px;
  }

  .article-item {
    padding-left: 12px;
  }
}

/* ---------- 无障碍与可读性 ---------- */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

::selection {
  background: rgba(59, 130, 246, 0.2);
  color: var(--text-heading);
}

:focus-visible {
  outline: 2px solid var(--primary-500);
  outline-offset: 2px;
}

/* ---------- 滚动条美化 ---------- */
::-webkit-scrollbar {
  width: 10px;
}

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

::-webkit-scrollbar-thumb {
  background: linear-gradient(180deg, var(--primary-500), var(--accent-500));
  border-radius: var(--radius-full);
  border: 2px solid var(--bg-body);
}

::-webkit-scrollbar-thumb:hover {
  background: linear-gradient(180deg, var(--primary-600), var(--accent-600));
}
```