/* ==========================================================================
   大象网络 (Daxiang Network) - 高性能纯原生 CSS 样式表
   ========================================================================== */

:root {
  --bg-color: #0b0f19;
  --bg-secondary: #111827;
  --bg-card: #1f293d;
  --bg-card-hover: #283552;
  --text-primary: #f9fafb;
  --text-secondary: #9ca3af;
  --text-muted: #6b7280;
  --accent-color: #3b82f6;
  --accent-hover: #2563eb;
  --accent-gradient: linear-gradient(135deg, #3b82f6 0%, #8b5cf6 100%);
  --accent-glow: rgba(59, 130, 246, 0.3);
  --border-color: rgba(255, 255, 255, 0.08);
  --border-highlight: rgba(59, 130, 246, 0.4);
  --success-color: #10b981;
  --warning-color: #f59e0b;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-full: 9999px;
  --shadow-card: 0 10px 30px -10px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 25px var(--accent-glow);
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif;
  --transition-fast: 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-smooth: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
  background-color: var(--bg-color);
  color: var(--text-primary);
  font-family: var(--font-sans);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

body {
  overflow-x: hidden;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

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

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

/* 通用容器 */
.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.section-padding {
  padding: 5rem 0;
}

/* 标题样式 */
.section-title {
  text-align: center;
  font-size: 2.25rem;
  font-weight: 800;
  margin-bottom: 1rem;
  letter-spacing: -0.025em;
  background: linear-gradient(180deg, #ffffff 0%, #cbd5e1 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.section-subtitle {
  text-align: center;
  color: var(--text-secondary);
  font-size: 1.125rem;
  max-width: 650px;
  margin: 0 auto 3.5rem auto;
}

/* 按钮规范 */
.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: all var(--transition-smooth);
  cursor: pointer;
  border: none;
  text-align: center;
  white-space: nowrap;
}

.btn-primary {
  background: var(--accent-gradient);
  color: #ffffff;
  box-shadow: 0 4px 14px 0 rgba(59, 130, 246, 0.39);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px 0 rgba(59, 130, 246, 0.6);
  opacity: 0.95;
}

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

.btn-secondary:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-highlight);
  transform: translateY(-2px);
}

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

.btn-block {
  width: 100%;
}

/* 顶部导航栏 */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(11, 15, 25, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
}

.navbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 80px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.5rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  color: #fff;
}

.logo-icon {
  width: 40px;
  height: 40px;
  background: var(--accent-gradient);
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  font-weight: 900;
  color: #ffffff;
  box-shadow: 0 0 15px var(--accent-glow);
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.5);
  line-height: 1;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 2rem;
  list-style: none;
}

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

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

/* 主视觉 Hero 区域 */
.hero {
  position: relative;
  padding: 7rem 0 5rem 0;
  background: radial-gradient(circle at 50% 20%, rgba(59, 130, 246, 0.15) 0%, transparent 60%);
  text-align: center;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.5rem 1.25rem;
  border-radius: var(--radius-full);
  background: rgba(59, 130, 246, 0.1);
  border: 1px solid rgba(59, 130, 246, 0.3);
  color: #60a5fa;
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 1.5rem;
}

.hero-title {
  font-size: 3.5rem;
  font-weight: 900;
  line-height: 1.15;
  margin-bottom: 1.5rem;
  letter-spacing: -0.03em;
}

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

.hero-desc {
  font-size: 1.25rem;
  color: var(--text-secondary);
  max-width: 750px;
  margin: 0 auto 2.5rem auto;
  line-height: 1.7;
}

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

.hero-features-bar {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
  max-width: 1000px;
  margin: 0 auto;
  padding: 1.5rem;
  background: rgba(31, 41, 61, 0.5);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  backdrop-filter: blur(8px);
}

.hero-feature-item {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
}

.hero-feature-icon {
  color: var(--success-color);
}

/* 核心优势卡片 */
.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-lg);
  padding: 2.25rem;
  transition: all var(--transition-smooth);
}

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

.feature-icon-wrapper {
  width: 56px;
  height: 56px;
  border-radius: var(--radius-md);
  background: rgba(59, 130, 246, 0.1);
  color: var(--accent-color);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.75rem;
  margin-bottom: 1.5rem;
}

.feature-card h3 {
  font-size: 1.35rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
}

.feature-card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.6;
}

/* 流媒体与 AI 支持 */
.support-section {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
}

.support-container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2.5rem;
}

.support-box {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2.5rem;
}

.support-box-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.support-box-header h3 {
  font-size: 1.5rem;
  font-weight: 700;
}

.tag-badge {
  padding: 0.25rem 0.75rem;
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  background: rgba(16, 185, 129, 0.15);
  color: var(--success-color);
}

.support-box p {
  color: var(--text-secondary);
  margin-bottom: 2rem;
  font-size: 0.95rem;
}

.support-tags-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
}

.support-tag {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.75rem 1rem;
  background: rgba(11, 15, 25, 0.6);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 600;
}

/* 价格套餐对比表 */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
  align-items: stretch;
}

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

.pricing-card:hover {
  transform: translateY(-5px);
  border-color: var(--border-highlight);
  box-shadow: var(--shadow-card);
}

.pricing-card.popular {
  border: 2px solid var(--accent-color);
  background: linear-gradient(180deg, rgba(31, 41, 61, 1) 0%, rgba(20, 29, 47, 1) 100%);
  box-shadow: var(--shadow-glow);
}

.popular-badge {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--accent-gradient);
  color: #fff;
  padding: 0.25rem 1rem;
  border-radius: var(--radius-full);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

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

.pricing-title {
  font-size: 1.35rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.pricing-price {
  font-size: 2.75rem;
  font-weight: 900;
  color: var(--text-primary);
  line-height: 1;
  margin: 1rem 0 0.5rem 0;
}

.pricing-price span {
  font-size: 1rem;
  font-weight: 500;
  color: var(--text-secondary);
}

.pricing-desc {
  font-size: 0.875rem;
  color: var(--text-secondary);
}

.pricing-features {
  list-style: none;
  margin-bottom: 2rem;
  flex-grow: 1;
}

.pricing-feature-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 0.925rem;
  margin-bottom: 0.9rem;
  color: var(--text-primary);
}

.pricing-feature-item.muted {
  color: var(--text-muted);
  text-decoration: line-through;
}

.check-icon {
  color: var(--success-color);
  flex-shrink: 0;
}

.cross-icon {
  color: var(--text-muted);
  flex-shrink: 0;
}

/* 用户评价 */
.testimonials-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
}

.testimonial-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 2rem;
}

.stars {
  color: #fbbf24;
  margin-bottom: 1rem;
  font-size: 1.1rem;
}

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

.user-info {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.user-avatar {
  width: 44px;
  height: 44px;
  border-radius: 50%;
  background: var(--accent-gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  color: #fff;
}

.user-name {
  font-weight: 700;
  font-size: 0.95rem;
}

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

/* FAQ 常见问题解答 */
.faq-container {
  max-width: 800px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}

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

.faq-item summary {
  padding: 1.35rem 1.75rem;
  font-size: 1.05rem;
  font-weight: 600;
  cursor: pointer;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
}

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

.faq-item summary::after {
  content: "+";
  font-size: 1.5rem;
  color: var(--accent-color);
  transition: transform var(--transition-fast);
}

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

.faq-answer {
  padding: 0 1.75rem 1.35rem 1.75rem;
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.6;
  border-top: 1px solid rgba(255, 255, 255, 0.04);
  padding-top: 1rem;
}

/* 底部页脚（按要求只保留四个标题入口） */
.footer {
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 3.5rem 0;
  margin-top: auto;
}

.footer-nav {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 2rem;
  text-align: center;
}

.footer-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
}

.footer-link {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-primary);
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-md);
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  width: 100%;
  max-width: 220px;
  transition: all var(--transition-smooth);
}

.footer-link:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-highlight);
  color: var(--accent-color);
  transform: translateY(-3px);
  box-shadow: var(--shadow-card);
}

.footer-copyright {
  text-align: center;
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  color: var(--text-muted);
  font-size: 0.85rem;
}

/* 子页面独立通用布局 (about, terms, privacy, sitemap) */
.page-header {
  padding: 4rem 0 2rem 0;
  text-align: center;
  background: radial-gradient(circle at 50% 0%, rgba(59, 130, 246, 0.1) 0%, transparent 60%);
}

.page-title {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 0.75rem;
}

.page-content {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 3rem;
  margin-bottom: 4rem;
}

.content-block {
  margin-bottom: 2.5rem;
}

.content-block:last-child {
  margin-bottom: 0;
}

.content-block h2 {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--accent-color);
  margin-bottom: 1rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.content-block p {
  color: var(--text-secondary);
  line-height: 1.8;
  margin-bottom: 1rem;
  font-size: 1rem;
}

.content-block ul {
  list-style-type: none;
  padding-left: 0;
}

.content-block li {
  position: relative;
  padding-left: 1.5rem;
  color: var(--text-secondary);
  margin-bottom: 0.75rem;
  line-height: 1.6;
}

.content-block li::before {
  content: "•";
  position: absolute;
  left: 0.5rem;
  color: var(--accent-color);
  font-weight: bold;
}

.breadcrumb {
  margin-bottom: 1.5rem;
  font-size: 0.9rem;
  color: var(--text-muted);
}

.breadcrumb a {
  color: var(--accent-color);
}

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

/* ==========================================================================
   移动端响应式适配媒体查询 (@media)
   ========================================================================== */

@media (max-width: 1024px) {
  .hero-title {
    font-size: 2.75rem;
  }
  
  .features-grid,
  .pricing-grid,
  .testimonials-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .support-container {
    grid-template-columns: 1fr;
  }
}

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

  .section-title {
    font-size: 1.75rem;
  }

  .navbar {
    height: 70px;
  }

  .nav-links {
    display: none; /* 移动端精简顶部，突出按钮 */
  }

  .hero {
    padding: 4rem 0 3rem 0;
  }

  .hero-title {
    font-size: 2.1rem;
  }

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

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

  .btn-large {
    width: 100%;
    min-height: 48px; /* 适合手指触摸 */
  }

  .hero-features-bar {
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
  }

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

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

  .footer-nav {
    grid-template-columns: 1fr;
    gap: 1rem;
  }

  .footer-link {
    max-width: 100%;
    min-height: 48px;
    display: flex;
    align-items: center;
    justify-content: center;
  }

  .page-content {
    padding: 1.5rem;
  }

  .page-title {
    font-size: 1.8rem;
  }
}