/* ==========================================================================
   海獭 (Otter) 网络加速器 - 极简高能响应式样式表
   Pure Vanilla CSS - 零外部依赖 - 毫秒秒开
   ========================================================================== */

/* --- 1. CSS 变量与设计系统 --- */
:root {
  /* 配色系统 - 极富科技感的深海光流 */
  --bg-dark: #070d19;
  --bg-card: #0f192e;
  --bg-card-hover: #162442;
  --bg-header: rgba(7, 13, 25, 0.85);
  
  --text-main: #f1f5f9;
  --text-muted: #94a3b8;
  --text-light: #64748b;
  
  --primary: #00f2fe;
  --primary-hover: #38ef7d;
  --secondary: #4facfe;
  --accent: #ff007a;
  --gradient-primary: linear-gradient(135deg, #00f2fe 0%, #4facfe 100%);
  --gradient-accent: linear-gradient(135deg, #ff007a 0%, #7928ca 100%);
  --gradient-gold: linear-gradient(135deg, #f6d365 0%, #fda085 100%);
  
  --border-color: rgba(255, 255, 255, 0.08);
  --border-glow: rgba(0, 242, 254, 0.3);
  
  --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 20px 25px -5px rgba(0, 0, 0, 0.5), 0 0 30px rgba(0, 242, 254, 0.15);
  --shadow-glow: 0 0 25px rgba(0, 242, 254, 0.35);
  
  --radius-sm: 8px;
  --radius-md: 16px;
  --radius-lg: 24px;
  --radius-full: 9999px;
  
  --font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --container-width: 1200px;
}

/* --- 2. 基础重置 --- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: var(--font-family);
  background-color: var(--bg-dark);
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  color: inherit;
  text-decoration: none;
  transition: all 0.25s ease;
}

ul, ol {
  list-style: none;
}

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

/* --- 3. 布局与容器 --- */
.container {
  width: 100%;
  max-width: var(--container-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: 1.25rem;
  padding-right: 1.25rem;
}

.section {
  padding: 5rem 0;
  position: relative;
}

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

.section-header {
  text-align: center;
  max-width: 700px;
  margin: 0 auto 3.5rem auto;
}

.section-badge {
  display: inline-block;
  padding: 0.35rem 1rem;
  background: rgba(0, 242, 254, 0.1);
  border: 1px solid var(--border-glow);
  color: var(--primary);
  border-radius: var(--radius-full);
  font-size: 0.875rem;
  font-weight: 600;
  letter-spacing: 0.5px;
  margin-bottom: 1rem;
}

.section-title {
  font-size: 2.5rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.2;
  margin-bottom: 1rem;
  background: linear-gradient(180deg, #ffffff 0%, #cbd5e1 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.section-subtitle {
  font-size: 1.125rem;
  color: var(--text-muted);
}

/* --- 4. 按钮系统 (适合手指触摸, min-height 48px) --- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.875rem 2rem;
  min-height: 48px; /* 触摸标准大小 */
  font-size: 1.05rem;
  font-weight: 700;
  border-radius: var(--radius-full);
  cursor: pointer;
  border: 2px solid transparent;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  white-space: nowrap;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.btn-primary {
  background: var(--gradient-primary);
  color: #030a16;
  box-shadow: var(--shadow-glow);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 0 35px rgba(0, 242, 254, 0.6);
  filter: brightness(1.1);
}

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

.btn-outline {
  background: rgba(255, 255, 255, 0.03);
  border-color: rgba(255, 255, 255, 0.2);
  color: var(--text-main);
}

.btn-outline:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: var(--primary);
  color: var(--primary);
}

.btn-lg {
  padding: 1rem 2.5rem;
  font-size: 1.15rem;
  min-height: 54px;
}

.btn-block {
  width: 100%;
}

/* --- 5. 导航栏 Header --- */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: var(--bg-header);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  height: 72px;
  display: flex;
  align-items: center;
}

.nav-wrapper {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.4rem;
  font-weight: 800;
  color: var(--text-main);
}

.brand-logo svg {
  width: 36px;
  height: 36px;
}

.brand-name {
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.nav-link {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--text-muted);
}

.nav-link:hover {
  color: var(--primary);
}

.header-cta {
  display: flex;
  align-items: center;
  gap: 1rem;
}

/* --- 6. 主视觉 Hero 区域 (左右分布 2 栏布局) --- */
.hero {
  padding-top: 8.5rem;
  padding-bottom: 5.5rem;
  position: relative;
  overflow: hidden;
  background: radial-gradient(circle at 50% 20%, rgba(0, 242, 254, 0.14) 0%, rgba(7, 13, 25, 0) 70%);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  align-items: center;
}

.hero-left {
  text-align: left;
}

.hero-headline {
  font-size: 3.25rem;
  font-weight: 900;
  line-height: 1.18;
  letter-spacing: -0.03em;
  margin-bottom: 1.25rem;
}

.gradient-text {
  background: var(--gradient-primary);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-size: 1.15rem;
  color: var(--text-muted);
  margin-bottom: 2rem;
  line-height: 1.6;
}

.hero-actions {
  display: flex;
  align-items: center;
  justify-content: flex-start;
  gap: 1rem;
  margin-bottom: 2.5rem;
  flex-wrap: wrap;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  background: rgba(15, 25, 46, 0.6);
  border: 1px solid var(--border-color);
  padding: 1.25rem;
  border-radius: var(--radius-md);
  backdrop-filter: blur(10px);
}

.stat-item h4 {
  font-size: 1.75rem;
  font-weight: 800;
  color: var(--primary);
  margin-bottom: 0.2rem;
}

.stat-item p {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* 右侧动态图卡 (Dynamic Card) */
.hero-right {
  position: relative;
  display: flex;
  justify-content: center;
}

.hero-dynamic-card {
  width: 100%;
  max-width: 480px;
  background: linear-gradient(145deg, rgba(15, 25, 46, 0.9) 0%, rgba(10, 20, 38, 0.95) 100%);
  border: 1px solid var(--border-glow);
  border-radius: var(--radius-lg);
  padding: 2rem;
  box-shadow: var(--shadow-lg);
  position: relative;
  overflow: hidden;
  backdrop-filter: blur(15px);
  animation: floatCard 6s ease-in-out infinite alternate;
}

.card-header-badge {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.5rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border-color);
}

.live-status {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--primary);
}

.status-dot {
  width: 10px;
  height: 10px;
  background-color: #00f2fe;
  border-radius: 50%;
  box-shadow: 0 0 10px #00f2fe;
  animation: pulseDot 1.8s infinite;
}

.speed-meter {
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  margin-bottom: 1.25rem;
}

.speed-val {
  font-size: 2.25rem;
  font-weight: 900;
  color: var(--primary);
  line-height: 1;
  margin-bottom: 0.5rem;
}

.speed-bar-container {
  width: 100%;
  height: 8px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: 4px;
  overflow: hidden;
}

.speed-bar-fill {
  height: 100%;
  width: 88%;
  background: var(--gradient-primary);
  border-radius: 4px;
  animation: barGlow 3s ease-in-out infinite alternate;
}

.node-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.node-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid rgba(255, 255, 255, 0.05);
  padding: 0.75rem 1rem;
  border-radius: var(--radius-sm);
  font-size: 0.875rem;
  transition: all 0.3s ease;
}

.node-item:hover {
  background: rgba(0, 242, 254, 0.08);
  border-color: var(--border-glow);
  transform: translateX(4px);
}

.node-ping {
  font-weight: 700;
  color: #38ef7d;
  font-size: 0.85rem;
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

/* CSS 微动画 Keyframes */
@keyframes floatCard {
  0% { transform: translateY(0px); }
  100% { transform: translateY(-12px); }
}

@keyframes pulseDot {
  0% { transform: scale(0.95); box-shadow: 0 0 0 0 rgba(0, 242, 254, 0.7); }
  70% { transform: scale(1.1); box-shadow: 0 0 0 8px rgba(0, 242, 254, 0); }
  100% { transform: scale(0.95); box-shadow: 0 0 0 0 rgba(0, 242, 254, 0); }
}

@keyframes barGlow {
  0% { width: 75%; }
  50% { width: 95%; }
  100% { width: 88%; }
}
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* --- 7. 产品核心优势 (3大卡片) --- */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 2.25rem 1.75rem;
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
}

.feature-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: var(--gradient-primary);
  opacity: 0;
  transition: opacity 0.3s ease;
}

.feature-card:hover {
  transform: translateY(-5px);
  background: var(--bg-card-hover);
  border-color: var(--border-glow);
  box-shadow: var(--shadow-lg);
}

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

.feature-icon {
  width: 60px;
  height: 60px;
  border-radius: var(--radius-md);
  background: rgba(0, 242, 254, 0.1);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary);
  margin-bottom: 1.5rem;
}

.feature-title {
  font-size: 1.35rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
}

.feature-desc {
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.6;
}

/* --- 8. 流媒体与 AI 支持卡片 --- */
.acceleration-section {
  background: linear-gradient(180deg, rgba(7, 13, 25, 0) 0%, rgba(15, 25, 46, 0.4) 50%, rgba(7, 13, 25, 0) 100%);
}

.accel-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.25rem;
}

.accel-card {
  background: rgba(15, 25, 46, 0.7);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.5rem 1.25rem;
  display: flex;
  align-items: center;
  gap: 1rem;
  transition: all 0.3s ease;
}

.accel-card:hover {
  border-color: var(--border-glow);
  background: var(--bg-card-hover);
  transform: scale(1.02);
}

.accel-logo {
  width: 48px;
  height: 48px;
  border-radius: 12px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  font-size: 1.2rem;
  flex-shrink: 0;
}

.accel-info h4 {
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 0.2rem;
}

.accel-info p {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* --- 9. 价格对比表 --- */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
  align-items: stretch;
}

.pricing-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2.5rem 2rem;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: all 0.3s ease;
}

.pricing-card.popular {
  background: linear-gradient(180deg, #112240 0%, #0a192f 100%);
  border: 2px solid var(--primary);
  box-shadow: var(--shadow-glow);
  transform: scale(1.03);
}

.popular-tag {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--gradient-primary);
  color: #030a16;
  padding: 0.25rem 1.25rem;
  border-radius: var(--radius-full);
  font-size: 0.8rem;
  font-weight: 800;
  letter-spacing: 0.5px;
  text-transform: uppercase;
}

.pricing-header {
  margin-bottom: 1.5rem;
}

.pricing-name {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-muted);
  margin-bottom: 0.5rem;
}

.pricing-price {
  display: flex;
  align-items: baseline;
  gap: 0.25rem;
}

.pricing-currency {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary);
}

.pricing-amount {
  font-size: 3rem;
  font-weight: 900;
  line-height: 1;
}

.pricing-period {
  color: var(--text-muted);
  font-size: 0.9rem;
}

.pricing-features {
  margin: 1.5rem 0 2rem 0;
  flex-grow: 1;
}

.pricing-feature-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 0.85rem;
  font-size: 0.95rem;
  color: var(--text-main);
}

.pricing-feature-item svg {
  color: var(--primary);
  flex-shrink: 0;
  width: 18px;
  height: 18px;
}

/* --- 10. 用户评价 --- */
.reviews-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.75rem;
}

.review-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.review-stars {
  color: #ffb703;
  margin-bottom: 1rem;
  display: flex;
  gap: 0.25rem;
}

.review-text {
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 1.5rem;
  font-style: italic;
}

.review-author {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.avatar {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-full);
  background: var(--gradient-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  color: #030a16;
}

.author-info h5 {
  font-size: 0.95rem;
  font-weight: 700;
}

.author-info p {
  font-size: 0.8rem;
  color: var(--text-light);
}

/* --- 11. FAQ 常见问题 (折叠原生 details/summary) --- */
.faq-list {
  max-width: 800px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color 0.3s ease;
}

.faq-item[open] {
  border-color: var(--border-glow);
}

.faq-summary {
  padding: 1.25rem 1.5rem;
  font-size: 1.1rem;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  user-select: none;
  list-style: none;
}

.faq-summary::-webkit-details-marker {
  display: none;
}

.faq-summary::after {
  content: '+';
  font-size: 1.4rem;
  font-weight: 400;
  color: var(--primary);
  transition: transform 0.3s ease;
}

.faq-item[open] .faq-summary::after {
  content: '−';
  transform: rotate(180deg);
}

.faq-content {
  padding: 0 1.5rem 1.25rem 1.5rem;
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.7;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  margin-top: 0.5rem;
  padding-top: 1rem;
}

/* --- 12. 极简规范页脚 Footer --- */
/* 用户需求约束：页脚只保留这四个标题，内容打开新的页面展示 */
.site-footer {
  margin-top: auto;
  background: #030812;
  border-top: 1px solid var(--border-color);
  padding: 2.5rem 0;
  text-align: center;
}

.footer-nav {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 2.5rem;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}

.footer-link {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--text-muted);
  padding: 0.5rem 0.75rem;
  min-height: 44px; /* 手指点击友好 */
  display: inline-flex;
  align-items: center;
}

.footer-link:hover {
  color: var(--primary);
  text-decoration: underline;
}

.footer-copyright {
  font-size: 0.85rem;
  color: var(--text-light);
}

/* --- 13. 独立子页面通用样式 (about, terms, privacy, sitemap) --- */
.page-header {
  padding-top: 8rem;
  padding-bottom: 3rem;
  background: radial-gradient(circle at 50% 0%, rgba(0, 242, 254, 0.08) 0%, rgba(7, 13, 25, 0) 70%);
  text-align: center;
  border-bottom: 1px solid var(--border-color);
}

.page-title {
  font-size: 2.75rem;
  font-weight: 800;
  margin-bottom: 0.75rem;
}

.page-content {
  padding: 4rem 0;
  max-width: 850px;
  margin: 0 auto;
}

.content-block {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 2.5rem;
  margin-bottom: 2rem;
}

.content-block h2 {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 1rem;
}

.content-block p {
  color: var(--text-muted);
  font-size: 1rem;
  line-height: 1.7;
  margin-bottom: 1rem;
}

.content-block ul {
  color: var(--text-muted);
  padding-left: 1.5rem;
  margin-bottom: 1rem;
}

.content-block li {
  list-style-type: disc;
  margin-bottom: 0.5rem;
  line-height: 1.6;
}

/* --- 14. 响应式适配：媒体查询 (@media) --- */

/* 移动端与平板中等屏适配 (<= 992px) */
@media (max-width: 992px) {
  .hero-grid {
    grid-template-columns: 1fr;
    gap: 2.5rem;
  }
  
  .hero-left {
    text-align: center;
  }
  
  .hero-actions {
    justify-content: center;
  }

  .hero-headline {
    font-size: 2.75rem;
  }
  
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .accel-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .pricing-grid {
    grid-template-columns: repeat(1, 1fr);
    max-width: 480px;
    margin: 0 auto;
  }

  .pricing-card.popular {
    transform: none;
  }
  
  .reviews-grid {
    grid-template-columns: repeat(1, 1fr);
  }
}

/* 手机端全单栏适配 (<= 768px) */
@media (max-width: 768px) {
  .section {
    padding: 3.5rem 0;
  }
  
  .section-title {
    font-size: 1.85rem;
  }
  
  .site-header {
    height: 64px;
  }
  
  .nav-links {
    display: none; /* 移动端精简顶部，聚焦极速 CTA */
  }
  
  .hero {
    padding-top: 6.5rem;
    padding-bottom: 4rem;
  }
  
  .hero-headline {
    font-size: 2rem;
    line-height: 1.25;
  }
  
  .hero-subtitle {
    font-size: 1rem;
    margin-bottom: 2rem;
  }
  
  /* 按钮适配：单栏全宽且适合手指点击 */
  .hero-actions {
    flex-direction: column;
    width: 100%;
    gap: 0.85rem;
  }
  
  .hero-actions .btn {
    width: 100%;
    min-height: 52px;
    font-size: 1.1rem;
  }
  
  .hero-stats {
    grid-template-columns: 1fr;
    gap: 1rem;
  }

  .stat-item h4 {
    font-size: 1.6rem;
  }
  
  /* 核心优势单栏化 */
  .features-grid {
    grid-template-columns: 1fr;
    gap: 1.25rem;
  }

  .feature-card {
    padding: 1.5rem 1.25rem;
  }

  /* 流媒体/AI 支撑卡片单栏化 */
  .accel-grid {
    grid-template-columns: 1fr;
    gap: 1rem;
  }

  /* 价格对比卡片全宽单栏 */
  .pricing-grid {
    grid-template-columns: 1fr;
    width: 100%;
  }

  .pricing-card {
    padding: 1.75rem 1.25rem;
  }

  .pricing-card .btn {
    width: 100%;
    min-height: 52px;
  }

  /* 页脚 4 项菜单单栏/分行排布，更大触控区域 */
  .footer-nav {
    flex-direction: column;
    gap: 0.75rem;
  }

  .footer-link {
    font-size: 1.1rem;
    padding: 0.6rem 1.2rem;
    width: 100%;
    max-width: 280px;
    justify-content: center;
    background: rgba(255, 255, 255, 0.03);
    border-radius: var(--radius-sm);
    border: 1px solid var(--border-color);
  }
  
  .content-block {
    padding: 1.5rem 1.25rem;
  }
}

/* 超小手机屏幕适配 (<= 480px) */
@media (max-width: 480px) {
  .container {
    padding-left: 1rem;
    padding-right: 1rem;
  }
  
  .hero-headline {
    font-size: 1.75rem;
  }
  
  .btn {
    padding: 0.85rem 1.25rem;
  }
}