/* ==========================================================================
   奈斯云 (NiceCloud) - 极速代理/加速服务 官方推广页样式表 (Light Theme)
   特性：纯 CSS 零依赖、高对比度浅色视觉、极致加载性能、完美响应式适配
   ========================================================================== */

/* 1. 全局变量定义 */
:root {
  --bg-primary: #f8fafc;
  --bg-surface: #ffffff;
  --bg-subtle: #f1f5f9;
  --bg-accent-light: #eff6ff;
  
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --text-white: #ffffff;
  
  --brand-primary: #2563eb;
  --brand-hover: #1d4ed8;
  --brand-light: #3b82f6;
  --brand-gradient: linear-gradient(135deg, #2563eb 0%, #4f46e5 100%);
  --brand-accent: #06b6d4;

  --border-color: #e2e8f0;
  --border-focus: #bfdbfe;
  
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.07), 0 2px 4px -2px rgba(0, 0, 0, 0.05);
  --shadow-lg: 0 10px 25px -5px rgba(37, 99, 235, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.04);
  --shadow-hover: 0 20px 30px -10px rgba(37, 99, 235, 0.15);

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-full: 9999px;
  
  --max-width: 1200px;
  --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 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: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  overflow-x: hidden;
}

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

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

ul, ol {
  list-style: none;
}

img, svg {
  max-width: 100%;
  height: auto;
  vertical-align: middle;
}

/* 3. 通用容器与排版 */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

.section {
  padding: 5rem 0;
}

.section-bg {
  background-color: var(--bg-surface);
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
}

.section-header {
  text-align: center;
  max-width: 760px;
  margin: 0 auto 3.5rem auto;
}

.badge-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.4rem 1rem;
  border-radius: var(--radius-full);
  background: var(--bg-accent-light);
  color: var(--brand-primary);
  font-size: 0.875rem;
  font-weight: 600;
  border: 1px solid #dbeafe;
  margin-bottom: 1rem;
}

.section-title {
  font-size: 2.25rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--text-primary);
  line-height: 1.25;
  margin-bottom: 1rem;
}

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

/* 4. 按钮规范 (CTA) */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.875rem 1.75rem;
  font-size: 1rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  transition: var(--transition);
  cursor: pointer;
  border: none;
  text-align: center;
  min-height: 48px;
  white-space: nowrap;
}

.btn-primary {
  background: var(--brand-gradient);
  color: var(--text-white) !important;
  box-shadow: 0 4px 14px 0 rgba(37, 99, 235, 0.35);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px 0 rgba(37, 99, 235, 0.45);
  color: var(--text-white) !important;
}

.btn-secondary {
  background-color: var(--bg-surface);
  color: var(--text-primary);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
}

.btn-secondary:hover {
  background-color: var(--bg-subtle);
  border-color: #cbd5e1;
  color: var(--brand-primary);
}

.btn-lg {
  padding: 1rem 2.25rem;
  font-size: 1.125rem;
  border-radius: var(--radius-lg);
}

.btn-block {
  width: 100%;
}

/* 5. 导航栏 (Header) */
.header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
  height: 72px;
  display: flex;
  align-items: center;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-primary);
}

.logo-icon {
  width: 36px;
  height: 36px;
  background: var(--brand-gradient);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.3);
}

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

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

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

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

/* 6. 主视觉区 (Hero Section) */
.hero {
  padding: 5rem 0 4rem 0;
  text-align: center;
  background: radial-gradient(circle at 50% 0%, #eff6ff 0%, var(--bg-primary) 70%);
}

.hero-content {
  max-width: 860px;
  margin: 0 auto;
}

.hero-title {
  font-size: 3.25rem;
  font-weight: 900;
  letter-spacing: -0.03em;
  line-height: 1.15;
  color: var(--text-primary);
  margin-bottom: 1.5rem;
}

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

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 2.5rem;
  max-width: 720px;
  margin-left: auto;
  margin-right: auto;
}

.hero-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.25rem;
  margin-bottom: 3.5rem;
  flex-wrap: wrap;
}

.hero-trust-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
  padding: 1.5rem;
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  margin-top: 2rem;
}

.trust-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  text-align: left;
}

.trust-icon {
  width: 42px;
  height: 42px;
  border-radius: var(--radius-md);
  background-color: var(--bg-accent-light);
  color: var(--brand-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.trust-title {
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--text-primary);
}

.trust-desc {
  font-size: 0.8rem;
  color: var(--text-muted);
}

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

.feature-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2rem;
  transition: var(--transition);
  box-shadow: var(--shadow-sm);
  position: relative;
  overflow: hidden;
}

.feature-card:hover {
  transform: translateY(-5px);
  border-color: #bfdbfe;
  box-shadow: var(--shadow-hover);
}

.feature-icon-wrapper {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  background: var(--bg-accent-light);
  color: var(--brand-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.25rem;
}

.feature-title {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
  color: var(--text-primary);
}

.feature-desc {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.55;
}

/* 8. 流媒体与 AI 支持专区 */
.ecosystem-container {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 3rem;
  box-shadow: var(--shadow-md);
}

.ecosystem-grid {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 1.5rem;
}

.eco-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 1.25rem 1rem;
  border-radius: var(--radius-md);
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  transition: var(--transition);
}

.eco-item:hover {
  border-color: var(--brand-light);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

.eco-icon {
  font-size: 2rem;
  margin-bottom: 0.5rem;
}

.eco-name {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-primary);
}

.eco-badge {
  font-size: 0.7rem;
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
  background: #dcfce7;
  color: #166534;
  margin-top: 0.3rem;
  font-weight: 600;
}

/* 9. 清晰套餐价格对比表 (Pricing Section) */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
  align-items: stretch;
}

.price-card {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2.25rem 1.75rem;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: var(--transition);
  box-shadow: var(--shadow-sm);
}

.price-card:hover {
  border-color: #cbd5e1;
  box-shadow: var(--shadow-md);
}

.price-card.featured {
  border: 2px solid var(--brand-primary);
  background-color: #ffffff;
  box-shadow: var(--shadow-lg);
  transform: scale(1.03);
}

.price-card.featured:hover {
  transform: scale(1.05);
}

.popular-tag {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--brand-gradient);
  color: var(--text-white);
  font-size: 0.8rem;
  font-weight: 700;
  padding: 0.25rem 1rem;
  border-radius: var(--radius-full);
  letter-spacing: 0.05em;
  box-shadow: 0 4px 10px rgba(37, 99, 235, 0.3);
}

.price-header {
  text-align: center;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 1.5rem;
}

.price-name {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 0.5rem;
}

.price-desc {
  font-size: 0.85rem;
  color: var(--text-muted);
  min-height: 2.5rem;
}

.price-amount-wrapper {
  margin: 1rem 0;
  display: flex;
  align-items: baseline;
  justify-content: center;
  gap: 0.25rem;
}

.currency {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--brand-primary);
}

.amount {
  font-size: 2.5rem;
  font-weight: 900;
  color: var(--text-primary);
  line-height: 1;
}

.period {
  font-size: 0.875rem;
  color: var(--text-muted);
}

.price-features {
  flex-grow: 1;
  margin-bottom: 2rem;
}

.price-feature-item {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-size: 0.9rem;
  color: var(--text-secondary);
  margin-bottom: 0.875rem;
}

.check-icon {
  width: 18px;
  height: 18px;
  color: #10b981;
  flex-shrink: 0;
}

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

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

.stars {
  color: #f59e0b;
  margin-bottom: 1rem;
  font-size: 1rem;
}

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

.review-author {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.author-avatar {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--brand-gradient);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1rem;
}

.author-info {
  display: flex;
  flex-direction: column;
}

.author-name {
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--text-primary);
}

.author-tag {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* 11. 常见问题解答 (FAQ Section) */
.faq-list {
  max-width: 820px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

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

.faq-item summary {
  padding: 1.25rem 1.5rem;
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--text-primary);
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

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

.faq-item summary::after {
  content: "+";
  font-size: 1.5rem;
  color: var(--brand-primary);
  font-weight: 400;
  transition: transform 0.2s ease;
}

.faq-item[open] summary::after {
  content: "−";
}

.faq-answer {
  padding: 0 1.5rem 1.25rem 1.5rem;
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.6;
  border-top: 1px dashed var(--border-color);
  padding-top: 1rem;
}

/* 12. 页脚规范 (Footer)
   严格规定：页脚只保留 4 个标题（网站地图、关于我们、服务条款、隐私政策），新页面打开 */
.footer {
  background-color: var(--bg-surface);
  border-top: 1px solid var(--border-color);
  padding: 3.5rem 0 2rem 0;
}

.footer-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2rem;
  text-align: center;
}

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

.footer-nav-link {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-primary);
  padding: 0.5rem 1rem;
  border-radius: var(--radius-sm);
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-color);
  transition: var(--transition);
}

.footer-nav-link:hover {
  background-color: var(--bg-accent-light);
  color: var(--brand-primary);
  border-color: #bfdbfe;
}

.footer-copyright {
  font-size: 0.875rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border-color);
  width: 100%;
  padding-top: 1.5rem;
  margin-top: 1rem;
}

/* 13. 子页面专用通用样式 (about.html, terms.html, privacy.html, sitemap.html) */
.page-header {
  padding: 3.5rem 0 2.5rem 0;
  background: var(--bg-accent-light);
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 3rem;
  text-align: center;
}

.page-title {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
}

.page-subtitle {
  font-size: 1.1rem;
  color: var(--text-secondary);
}

.content-box {
  background-color: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2.5rem;
  box-shadow: var(--shadow-sm);
  margin-bottom: 3rem;
}

.content-box h2 {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--text-primary);
  margin: 2rem 0 1rem 0;
  padding-bottom: 0.5rem;
  border-bottom: 2px solid var(--bg-accent-light);
}

.content-box h2:first-child {
  margin-top: 0;
}

.content-box p {
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 1.25rem;
  font-size: 1rem;
}

.content-box ul {
  margin-bottom: 1.5rem;
  padding-left: 1.25rem;
}

.content-box li {
  list-style: disc;
  color: var(--text-secondary);
  margin-bottom: 0.5rem;
  line-height: 1.6;
}

.nodes-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.25rem;
  margin: 1.5rem 0;
}

.node-card {
  background-color: var(--bg-primary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.flag {
  font-size: 1.75rem;
}

.node-info h4 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-primary);
}

.node-info p {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-bottom: 0;
}

.sitemap-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 2rem;
}

.sitemap-group h3 {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--brand-primary);
  margin-bottom: 1rem;
}

.sitemap-list li {
  list-style: none;
  margin-bottom: 0.75rem;
}

.sitemap-list a {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 500;
}

/* 14. 完美响应式媒体查询 (@media) */
@media (max-width: 1024px) {
  .pricing-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
  }
  
  .price-card.featured {
    transform: none;
  }
  
  .price-card.featured:hover {
    transform: none;
  }

  .ecosystem-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .hero-trust-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .nodes-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .section {
    padding: 3.5rem 0;
  }

  .hero {
    padding: 3rem 0 2.5rem 0;
  }

  .hero-title {
    font-size: 2.25rem;
  }

  .hero-subtitle {
    font-size: 1.05rem;
  }

  .nav-links {
    display: none;
  }

  .features-grid, .reviews-grid, .pricing-grid {
    grid-template-columns: 1fr;
  }

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

  .hero-trust-grid {
    grid-template-columns: 1fr;
  }

  .footer-nav-list {
    flex-direction: column;
    gap: 1rem;
    width: 100%;
  }

  .footer-nav-link {
    width: 100%;
    display: block;
    text-align: center;
  }

  .btn {
    width: 100%;
  }

  .hero-actions {
    flex-direction: column;
    width: 100%;
  }

  .nodes-grid, .sitemap-grid {
    grid-template-columns: 1fr;
  }
  
  .content-box {
    padding: 1.5rem;
  }
}