```css
/* ===== 蘑菇视频 - 完整样式表 ===== */
:root {
  --bg-primary: #f8fafc;
  --bg-card: #ffffff;
  --bg-footer: #1e293b;
  --bg-nav: rgba(255, 255, 255, 0.8);
  --text-primary: #1f2937;
  --text-secondary: #3e4c59;
  --text-heading: #0f172a;
  --text-footer: #e2e8f0;
  --text-footer-muted: #cbd5e1;
  --accent: #2563eb;
  --accent-dark: #1e40af;
  --border-light: #cbd5e1;
  --shadow: 0 4px 12px rgba(0, 0, 0, 0.06);
  --radius: 20px;
  --glass-bg: rgba(255, 255, 255, 0.6);
  --glass-border: rgba(255, 255, 255, 0.3);
  --gradient-primary: linear-gradient(145deg, #1e3a8a, #0f172a);
  --gradient-accent: linear-gradient(135deg, #2563eb, #7c3aed);
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="dark"] {
  --bg-primary: #0b1120;
  --bg-card: #1e293b;
  --bg-footer: #0f172a;
  --bg-nav: rgba(17, 24, 39, 0.85);
  --text-primary: #e2e8f0;
  --text-secondary: #cbd5e1;
  --text-heading: #f8fafc;
  --text-footer: #e2e8f0;
  --text-footer-muted: #94a3b8;
  --accent: #60a5fa;
  --accent-dark: #3b82f6;
  --border-light: #334155;
  --glass-bg: rgba(30, 41, 59, 0.6);
  --glass-border: rgba(255, 255, 255, 0.1);
  --gradient-primary: linear-gradient(145deg, #1e293b, #0f172a);
  --gradient-accent: linear-gradient(135deg, #3b82f6, #8b5cf6);
}

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

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
}

body {
  font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.7;
  transition: background 0.3s ease, color 0.3s ease;
  overflow-x: hidden;
}

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

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

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

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

.container {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 24px;
}

/* ===== 导航 ===== */
nav {
  background: var(--bg-nav);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  box-shadow: 0 2px 20px rgba(0, 0, 0, 0.08);
  position: sticky;
  top: 0;
  z-index: 1000;
  border-bottom: 1px solid var(--glass-border);
  transition: var(--transition);
}

.nav-wrap {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 70px;
}

.logo {
  font-weight: 700;
  font-size: 1.6rem;
  color: var(--text-heading);
  display: flex;
  align-items: center;
  gap: 8px;
  text-decoration: none;
  transition: var(--transition);
}

.logo:hover {
  transform: scale(1.05);
}

.logo svg {
  width: 36px;
  height: 36px;
  border-radius: 8px;
}

.nav-links {
  display: flex;
  gap: 28px;
  align-items: center;
}

.nav-links a {
  color: var(--text-primary);
  text-decoration: none;
  font-weight: 500;
  font-size: 1rem;
  transition: var(--transition);
  position: relative;
  padding: 4px 0;
}

.nav-links a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: var(--accent);
  transition: width 0.3s ease;
}

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

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

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

.search-box {
  display: flex;
  align-items: center;
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  border: 1px solid var(--glass-border);
  border-radius: 40px;
  padding: 6px 14px;
  transition: var(--transition);
}

.search-box:focus-within {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.search-box input {
  border: none;
  background: transparent;
  color: var(--text-primary);
  padding: 6px;
  width: 160px;
  outline: none;
  font-size: 0.95rem;
}

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

.search-box button {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--text-secondary);
  font-size: 1.1rem;
  transition: var(--transition);
}

.search-box button:hover {
  color: var(--accent);
  transform: scale(1.1);
}

.theme-toggle {
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  border: 1px solid var(--glass-border);
  border-radius: 30px;
  padding: 6px 14px;
  color: var(--text-primary);
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
  font-size: 0.9rem;
}

.theme-toggle:hover {
  border-color: var(--accent);
  transform: scale(1.05);
}

.mobile-menu-btn {
  display: none;
  background: none;
  border: 0;
  font-size: 2rem;
  color: var(--text-primary);
  cursor: pointer;
  padding: 4px;
  transition: var(--transition);
}

.mobile-menu-btn:hover {
  color: var(--accent);
  transform: scale(1.1);
}

/* 移动菜单 */
.mobile-nav {
  display: none;
  flex-direction: column;
  background: var(--bg-nav);
  backdrop-filter: blur(20px);
  padding: 16px;
  border-top: 1px solid var(--glass-border);
  animation: slideDown 0.3s ease;
}

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

.mobile-nav a {
  padding: 12px 0;
  border-bottom: 1px solid var(--glass-border);
  color: var(--text-primary);
  text-decoration: none;
  font-weight: 500;
  transition: var(--transition);
}

.mobile-nav a:hover {
  color: var(--accent);
  padding-left: 8px;
}

.mobile-nav a:last-child {
  border-bottom: none;
}

/* ===== 按钮 ===== */
.btn {
  background: var(--accent);
  color: #fff;
  border: none;
  padding: 12px 28px;
  border-radius: 40px;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  font-size: 1rem;
  display: inline-block;
  text-decoration: none;
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  background: rgba(255, 255, 255, 0.2);
  border-radius: 50%;
  transform: translate(-50%, -50%);
  transition: width 0.6s, height 0.6s;
}

.btn:hover {
  background: var(--accent-dark);
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(37, 99, 235, 0.3);
}

.btn:hover::before {
  width: 300px;
  height: 300px;
}

.btn:active {
  transform: translateY(0);
}

/* ===== 卡片 ===== */
.card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
  border: 1px solid rgba(0, 0, 0, 0.03);
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: linear-gradient(135deg, transparent 0%, rgba(255, 255, 255, 0.1) 100%);
  opacity: 0;
  transition: opacity 0.3s ease;
}

.card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 24px rgba(0, 0, 0, 0.1);
}

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

/* ===== 标题层级 ===== */
h1, h2, h3, h4 {
  color: var(--text-heading);
  line-height: 1.3;
}

h1 {
  font-size: 2.6rem;
  font-weight: 800;
  margin-bottom: 16px;
  background: var(--gradient-accent);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

h2 {
  font-size: 2.1rem;
  font-weight: 700;
  margin: 32px 0 16px;
  position: relative;
  display: inline-block;
}

h2::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 60px;
  height: 3px;
  background: var(--gradient-accent);
  border-radius: 3px;
}

h3 {
  font-size: 1.5rem;
  font-weight: 600;
  margin: 24px 0 12px;
}

h4 {
  font-size: 1.2rem;
  font-weight: 600;
  margin: 16px 0 8px;
}

p {
  color: var(--text-primary);
  margin-bottom: 16px;
}

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

a:hover {
  color: var(--accent-dark);
}

.text-secondary {
  color: var(--text-secondary);
}

/* ===== Banner ===== */
.banner {
  background: var(--gradient-primary);
  border-radius: 32px;
  padding: 48px 40px;
  color: white;
  margin: 28px 0;
  position: relative;
  overflow: hidden;
}

.banner::before {
  content: '';
  position: absolute;
  top: -50%;
  right: -20%;
  width: 300px;
  height: 300px;
  background: radial-gradient(circle, rgba(255, 255, 255, 0.1) 0%, transparent 70%);
  animation: float 6s ease-in-out infinite;
}

.banner::after {
  content: '';
  position: absolute;
  bottom: -50%;
  left: -20%;
  width: 300px;
  height: 300px;
  background: radial-gradient(circle, rgba(255, 255, 255, 0.05) 0%, transparent 70%);
  animation: float 8s ease-in-out infinite reverse;
}

@keyframes float {
  0%, 100% {
    transform: translate(0, 0);
  }
  50% {
    transform: translate(20px, -20px);
  }
}

.banner h2, .banner p {
  color: #fff;
  position: relative;
  z-index: 1;
}

.banner h2 {
  font-size: 2.4rem;
  margin-bottom: 16px;
}

.banner p {
  font-size: 1.1rem;
  opacity: 0.9;
  max-width: 600px;
}

.banner .btn {
  background: #fff;
  color: #1e3a8a;
  margin-top: 16px;
  position: relative;
  z-index: 1;
}

.banner .btn:hover {
  background: #f0f0f0;
  transform: translateY(-2px);
  box-shadow: 0 8px 20px rgba(255, 255, 255, 0.2);
}

/* ===== 网格布局 ===== */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

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

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

.footer::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: var(--gradient-accent);
}

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

.footer a:hover {
  color: #fff;
  transform: translateX(4px);
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 24px;
}

.footer-links a {
  padding: 4px 0;
  position: relative;
}

.footer-links a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 1px;
  background: #fff;
  transition: width 0.3s ease;
}

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

/* ===== FAQ ===== */
.faq-item {
  border-bottom: 1px solid var(--border-light);
  padding: 12px 0;
  transition: var(--transition);
}

.faq-item:last-child {
  border-bottom: none;
}

.faq-question {
  display: flex;
  justify-content: space-between;
  cursor: pointer;
  font-weight: 600;
  color: var(--text-heading);
  padding: 12px;
  border-radius: 8px;
  transition: var(--transition);
}

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

.faq-question span {
  font-size: 1.5rem;
  transition: transform 0.3s ease;
}

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

.faq-answer {
  padding: 12px;
  color: var(--text-primary);
  animation: fadeIn 0.3s ease;
}

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

/* ===== HowTo ===== */
.howto-step {
  background: var(--bg-card);
  border-left: 6px solid var(--accent);
  padding: 16px;
  margin: 12px 0;
  border-radius: 0 12px 12px 0;
  transition: var(--transition);
}

.howto-step:hover {
  transform: translateX(8px);
  box-shadow: var(--shadow);
}

.howto-step strong {
  color: var(--accent);
  margin-right: 8px;
}

/* ===== 返回顶部 ===== */
.back-to-top {
  position: fixed;
  bottom: 30px;
  right: 30px;
  background: var(--gradient-accent);
  color: white;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
  border: none;
  font-size: 1.8rem;
  z-index: 2000;
  transition: var(--transition);
  opacity: 0;
  transform: translateY(20px);
}

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

.back-to-top:hover {
  transform: translateY(-4px);
  box-shadow: 0 8px 20px rgba(37, 99, 235, 0.4);
}

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

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* 延迟动画 */
.delay-1 { transition-delay: 0.1s; }
.delay-2 { transition-delay: 0.2s; }
.delay-3 { transition-delay: 0.3s; }

/* ===== 友情链接 ===== */
.friend-links a {
  display: inline-block;
  padding: 8px 16px;
  margin: 4px;
  background: var(--glass-bg);
  border: 1px solid var(--glass-border);
  border-radius: 20px;
  transition: var(--transition);
}

.friend-links a:hover {
  background: var(--accent);
  color: #fff;
  transform: translateY(-2px);
}

/* ===== 联系卡片 ===== */
.contact-card {
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius);
  padding: 24px;
  transition: var(--transition);
}

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

/* ===== 响应式 ===== */
@media (max-width: 900px) {
  .nav-links {
    display: none;
  }
  
  .mobile-menu-btn {
    display: block;
  }
  
  .search-box input {
    width: 100px;
  }
  
  .search-box input:focus {
    width: 140px;
  }
  
  h1 {
    font-size: 2rem;
  }
  
  h2 {
    font-size: 1.8rem;
  }
  
  .banner {
    padding: 32px 24px;
  }
  
  .banner h2 {
    font-size: 1.8rem;
  }
  
  .back-to-top {
    bottom: 20px;
    right: 20px;
    width: 40px;
    height: 40px;
    font-size: 1.5rem;
  }
}

@media (max-width: 800px) {
  .grid-2,
  .grid-3 {
    grid-template-columns: 1fr;
  }
  
  .container {
    padding: 0 16px;
  }
  
  .nav-wrap {
    height: 60px;
  }
  
  .logo {
    font-size: 1.3rem;
  }
  
  .logo svg {
    width: 30px;
    height: 30px;
  }
  
  .search-box {
    display: none;
  }
  
  .theme-toggle {
    font-size: 0.8rem;
    padding: 4px 10px;
  }
  
  .banner {
    padding: 24px 16px;
    border-radius: 24px;
  }
  
  .banner h2 {
    font-size: 1.5rem;
  }
  
  .banner p {
    font-size: 0.95rem;
  }
  
  .btn {
    padding: 10px 20px;
    font-size: 0.9rem;
  }
  
  .card {
    padding: 16px;
    border-radius: 16px;
  }
  
  .footer {
    padding: 32px 0;
  }
  
  .footer-links {
    gap: 12px;
    flex-direction: column;
  }
  
  .back-to-top {
    bottom: 16px;
    right: 16px;
    width: 36px;
    height: 36px;
    font-size: 1.3rem;
  }
}

@media (max-width: 480px) {
  h1 {
    font-size: 1.6rem;
  }
  
  h2 {
    font-size: 1.4rem;
  }
  
  h3 {
    font-size: 1.2rem;
  }
  
  .banner h2 {
    font-size: 1.3rem;
  }
  
  .banner p {
    font-size: 0.85rem;
  }
  
  .banner .btn {
    padding: 8px 16px;
    font-size: 0.85rem;
  }
  
  .theme-toggle {
    display: none;
  }
  
  .mobile-menu-btn {
    font-size: 1.6rem;
  }
}

/* ===== 打印样式 ===== */
@media print {
  nav,
  .back-to-top,
  .mobile-menu-btn,
  .theme-toggle,
  .search-box {
    display: none !important;
  }
  
  body {
    background: white;
    color: black;
  }
  
  .card {
    box-shadow: none;
    border: 1px solid #ccc;
  }
}

/* ===== 无障碍 ===== */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

/* ===== 键盘焦点 ===== */
:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 2px;
}

/* ===== 选择文本 ===== */
::selection {
  background: var(--accent);
  color: white;
}

/* ===== 高亮 ===== */
mark {
  background: rgba(37, 99, 235, 0.2);
  color: var(--text-heading);
  padding: 2px 4px;
  border-radius: 4px;
}

/* ===== 响应式字体 ===== */
@media (min-width: 1200px) {
  html {
    font-size: 18px;
  }
}

@media (max-width: 600px) {
  html {
    font-size: 15px;
  }
}

/* ===== 额外样式 ===== */
.section-padding {
  padding: 40px 0;
}

.mt-1 { margin-top: 8px; }
.mt-2 { margin-top: 16px; }
.mt-3 { margin-top: 24px; }
.mt-4 { margin-top: 32px; }
.mt-5 { margin-top: 40px; }

.mb-1 { margin-bottom: 8px; }
.mb-2 { margin-bottom: 16px; }
.mb-3 { margin-bottom: 24px; }
.mb-4 { margin-bottom: 32px; }
.mb-5 { margin-bottom: 40px; }

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.flex { display: flex; }
.flex-wrap { flex-wrap: wrap; }
.flex-center { justify-content: center; align-items: center; }
.gap-1 { gap: 8px; }
.gap-2 { gap: 16px; }
.gap-3 { gap: 24px; }

.rounded { border-radius: var(--radius); }
.shadow { box-shadow: var(--shadow); }
.bg-card { background: var(--bg-card); }

/* ===== 品牌色 ===== */
.brand-primary { color: var(--accent); }
.brand-dark { color: var(--accent-dark); }

/* ===== 新闻卡片 ===== */
.news-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 20px;
  box-shadow: var(--shadow);
  transition: var(--transition);
  border: 1px solid rgba(0, 0, 0, 0.03);
}

.news-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 24px rgba(0, 0, 0, 0.1);
}

.news-card .date {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-bottom: 8px;
  display: block;
}

.news-card h3 {
  font-size: 1.2rem;
  margin-bottom: 12px;
  color: var(--text-heading);
  transition: var(--transition);
}

.news-card:hover h3 {
  color: var(--accent);
}

.news-card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.6;
  margin-bottom: 12px;
}

.news-card a {
  color: var(--accent);
  font-weight: 500;
  text-decoration: none;
  transition: var(--transition);
}

.news-card a:hover {
  color: var(--accent-dark);
  padding-left: 4px;
}

/* ===== 案例卡片 ===== */
.case-card {
  background: var(--bg-card);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
  transition: var(--transition);
  border: 1px solid rgba(0, 0, 0, 0.03);
  position: relative;
  overflow: hidden;
}

.case-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: var(--gradient-accent);
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.4s ease;
}

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

.case-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 24px rgba(0, 0, 0, 0.1);
}

/* ===== 联系表单 ===== */
.contact-form input,
.contact-form textarea {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--border-light);
  border-radius: 12px;
  background: var(--bg-card);
  color: var(--text-primary);
  font-size: 1rem;
  transition: var(--transition);
  margin-bottom: 16px;
}

.contact-form input:focus,
.contact-form textarea:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.contact-form textarea {
  min-height: 120px;
  resize: vertical;
}

/* ===== 图标动画 ===== */
.svg-icon {
  width: 24px;
  height: 24px;
  fill: currentColor;
  transition: var(--transition);
}

.svg-icon:hover {
  transform: scale(1.2);
}

/* ===== 分隔线 ===== */
.divider {
  width: 100%;
  height: 1px;
  background: var(--border-light);
  margin: 32px 0;
}

/* ===== 徽章 ===== */
.badge {
  display: inline-block;
  padding: 4px 12px;
  background: var(--gradient-accent);
  color: white;
  border-radius: 20px;
  font-size: 0.85rem;
  font-weight: 600;
  transition: var(--transition);
}

.badge:hover {
  transform: scale(1.05);
}

/* ===== 暗色模式优化 ===== */
[data-theme="dark"] .card {
  border-color: rgba(255, 255, 255, 0.05);
}

[data-theme="dark"] .banner {
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
}

[data-theme="dark"] .back-to-top {
  background: var(--gradient-accent);
}

/* ===== 性能优化 ===== */
@media (max-width: 768px) {
  .grid-2,
  .grid-3 {
    gap: 16px;
  }
  
  .card {
    padding: 16px;
  }
}

/* ===== 最终优化 ===== */
img {
  max-width: 100%;
  height: auto;
  display: block;
}

video {
  max-width: 100%;
  height: auto;
}

iframe {
  max-width: 100%;
  border: none;
}

/* ===== 结束 ===== */
```