:root {
  /* 品牌核心主色调：深墨黑 × 极光青 × 电光青柠 */
  --bg-primary: #071C21;
  --bg-secondary: #0c242a;
  --bg-card: #102C30;
  --bg-card-hover: #163a3f;
  --border-color: #2B4C4C;
  --border-glow: rgba(36, 231, 218, 0.38);
  
  --text-primary: #F1F9F7;
  --text-secondary: #A5B9B8;
  --text-muted: #6f8a89;
  
  --accent-cyan: #24E7DA;
  --accent-lime: #B8F730;
  --accent-gradient: linear-gradient(135deg, #24E7DA 0%, #15b8ad 100%);
  --lime-gradient: linear-gradient(135deg, #B8F730 0%, #8ec41a 100%);
  
  --shadow-sm: 0 4px 14px rgba(0, 0, 0, 0.35);
  --shadow-lg: 0 12px 36px rgba(0, 0, 0, 0.55);
  
  --max-width: 1200px;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --nav-height: 72px;
}

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

html {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
  background-color: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
  background-color: var(--bg-primary);
}

/* Accessibility */
.skip-link {
  position: absolute;
  top: -60px;
  left: 16px;
  background: var(--accent-cyan);
  color: #071C21;
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  font-weight: 700;
  z-index: 9999;
  text-decoration: none;
  transition: top 0.2s ease;
}
.skip-link:focus {
  top: 16px;
}

:focus-visible {
  outline: 2px solid var(--accent-cyan);
  outline-offset: 3px;
}

/* Typography & Layout */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

section {
  padding: 85px 0;
  scroll-margin-top: calc(var(--nav-height) + 20px);
}

.section-header {
  text-align: center;
  max-width: 760px;
  margin: 0 auto 52px auto;
}

.section-tag {
  display: inline-block;
  padding: 5px 16px;
  border-radius: 30px;
  background: rgba(36, 231, 218, 0.1);
  color: var(--accent-cyan);
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 14px;
  border: 1px solid rgba(36, 231, 218, 0.28);
}

.section-title {
  font-size: 2.25rem;
  font-weight: 800;
  color: var(--text-primary);
  margin-bottom: 16px;
  letter-spacing: -0.02em;
}

.section-desc {
  font-size: 1.05rem;
  color: var(--text-secondary);
}

/* Text Highlights */
.highlight-cyan {
  color: var(--accent-cyan);
}

.highlight-lime {
  color: var(--accent-lime);
}

/* Navigation Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  height: var(--nav-height);
  background: rgba(7, 28, 33, 0.92);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
}

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

.brand-logo {
  display: inline-flex;
  align-items: center;
  text-decoration: none;
}

.brand-logo-img {
  height: 38px;
  width: auto;
  max-width: 175px;
  object-fit: contain;
  display: block;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 28px;
  list-style: none;
}

.nav-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  transition: color 0.2s ease;
  padding: 8px 0;
}

.nav-link:hover, .nav-link.active {
  color: var(--accent-cyan);
}

.nav-actions {
  display: flex;
  align-items: center;
  gap: 16px;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 26px;
  min-height: 44px;
  min-width: 44px;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 700;
  text-decoration: none;
  cursor: pointer;
  transition: all 0.22s ease;
  border: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--accent-gradient);
  color: #071C21;
  box-shadow: 0 4px 18px rgba(36, 231, 218, 0.35);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 26px rgba(36, 231, 218, 0.55);
  background: linear-gradient(135deg, #37ede1 0%, #17c9bd 100%);
}

.btn-outline {
  background: transparent;
  color: var(--text-primary);
  border: 1px solid var(--border-color);
}

.btn-outline:hover {
  border-color: var(--accent-cyan);
  color: var(--accent-cyan);
  background: rgba(36, 231, 218, 0.08);
  transform: translateY(-2px);
}

.btn-sm {
  padding: 8px 18px;
  font-size: 0.88rem;
  min-height: 40px;
}

/* Hero Section with fastlink-hero-2560x1440.webp & Silky Light Flow */
.hero-section {
  position: relative;
  padding: 115px 0 90px 0;
  background-color: var(--bg-primary);
  background-image:
    linear-gradient(180deg, rgba(7, 28, 33, 0.72) 0%, rgba(7, 28, 33, 0.86) 65%, #071C21 100%),
    url("public/assets/fastlink/fastlink-hero-2560x1440.webp");
  background-size: cover;
  background-position: center top;
  background-repeat: no-repeat;
  text-align: center;
  overflow: hidden;
}

/* 微弱、极其缓慢、丝滑的环境光流动效果（纯原生轻量 CSS 动画） */
.hero-section::before {
  content: "";
  position: absolute;
  top: -40%;
  left: -40%;
  width: 180%;
  height: 180%;
  background: radial-gradient(circle at 50% 35%, rgba(36, 231, 218, 0.12) 0%, rgba(184, 247, 48, 0.05) 35%, transparent 68%);
  pointer-events: none;
  animation: heroLightFlow 24s ease-in-out infinite alternate;
  will-change: transform, opacity;
  z-index: 1;
}

@keyframes heroLightFlow {
  0% {
    transform: translate3d(-3%, -2%, 0) scale(1);
    opacity: 0.7;
  }
  50% {
    transform: translate3d(2%, 1%, 0) scale(1.05);
    opacity: 0.95;
  }
  100% {
    transform: translate3d(3%, -1%, 0) scale(1);
    opacity: 0.75;
  }
}

.hero-content {
  position: relative;
  z-index: 2;
  max-width: 880px;
  margin: 0 auto;
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 18px;
  border-radius: 40px;
  background: rgba(184, 247, 48, 0.12);
  color: var(--accent-lime);
  font-size: 0.88rem;
  font-weight: 700;
  border: 1px solid rgba(184, 247, 48, 0.35);
  margin-bottom: 24px;
}

.hero-title {
  font-size: 3rem;
  font-weight: 900;
  line-height: 1.22;
  margin-bottom: 20px;
  letter-spacing: -0.03em;
  color: #FFFFFF;
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--text-primary);
  font-weight: 600;
  margin-bottom: 22px;
}

.hero-intro {
  font-size: 1.1rem;
  color: var(--text-secondary);
  line-height: 1.75;
  margin-bottom: 38px;
}

.hero-cta-group {
  display: flex;
  justify-content: center;
  gap: 18px;
  flex-wrap: wrap;
  margin-bottom: 44px;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  padding: 24px;
  background: rgba(16, 44, 48, 0.85);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  margin-top: 30px;
}

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

.stat-num {
  font-size: 1.85rem;
  font-weight: 800;
  color: var(--accent-cyan);
  display: block;
}

.stat-label {
  font-size: 0.85rem;
  color: var(--text-muted);
}

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

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 34px 28px;
  transition: all 0.25s ease;
  position: relative;
  overflow: hidden;
}

.feature-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-glow);
  box-shadow: var(--shadow-lg);
  background: var(--bg-card-hover);
}

.card-icon-box {
  width: 52px;
  height: 52px;
  border-radius: 12px;
  background: rgba(36, 231, 218, 0.1);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 20px;
  color: var(--accent-cyan);
  border: 1px solid rgba(36, 231, 218, 0.2);
}

.feature-title {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 12px;
  color: var(--text-primary);
}

.feature-desc {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.65;
}

/* Streaming & AI Cards */
.stream-ai-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.stream-card {
  background: linear-gradient(145deg, var(--bg-card) 0%, rgba(12, 36, 42, 0.8) 100%);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 36px;
  position: relative;
  transition: border-color 0.25s ease;
}

.stream-card:hover {
  border-color: var(--border-glow);
}

.stream-card-title {
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 12px;
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 20px 0;
}

.tag-badge {
  padding: 5px 12px;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-color);
  border-radius: 6px;
  font-size: 0.82rem;
  color: var(--text-secondary);
}

/* Pricing Table */
.pricing-wrapper {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  margin-bottom: 24px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background: var(--bg-card);
}

.pricing-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
}

.pricing-table caption {
  text-align: left;
  font-size: 0.9rem;
  color: var(--text-muted);
  padding: 16px 24px;
  border-bottom: 1px solid var(--border-color);
}

.pricing-table th, .pricing-table td {
  padding: 18px 24px;
  border-bottom: 1px solid var(--border-color);
  font-size: 0.95rem;
  white-space: nowrap;
}

.pricing-table td:last-child {
  min-width: 120px;
}

.pricing-table .btn {
  white-space: nowrap;
  min-width: 100px;
  width: auto;
}

.pricing-table th {
  background: var(--bg-secondary);
  color: var(--text-primary);
  font-weight: 700;
  text-transform: uppercase;
  font-size: 0.85rem;
  letter-spacing: 0.05em;
}

.pricing-table tbody tr:hover {
  background: var(--bg-card-hover);
}

.tier-name {
  font-weight: 700;
  color: var(--text-primary);
  font-size: 1.05rem;
}

.price-val {
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--accent-cyan);
}

.price-period {
  font-size: 0.82rem;
  color: var(--text-muted);
}

.badge-rec {
  background: linear-gradient(135deg, #24E7DA 0%, #B8F730 100%);
  color: #071C21;
  padding: 3px 8px;
  border-radius: 4px;
  font-size: 0.72rem;
  margin-left: 6px;
  font-weight: 800;
}

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

.review-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 30px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: all 0.25s ease;
}

.review-card:hover {
  border-color: var(--border-glow);
  transform: translateY(-3px);
}

.review-stars {
  color: #ffb703;
  font-size: 1.1rem;
  margin-bottom: 12px;
}

.review-body {
  font-size: 0.95rem;
  color: var(--text-secondary);
  line-height: 1.65;
  margin-bottom: 20px;
}

.reviewer-meta {
  display: flex;
  align-items: center;
  gap: 12px;
}

.reviewer-avatar {
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: rgba(36, 231, 218, 0.12);
  border: 1px solid rgba(36, 231, 218, 0.3);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  color: var(--accent-cyan);
}

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

.reviewer-info p {
  font-size: 0.82rem;
  color: var(--text-muted);
}

/* FAQ Details/Summary (Default Open) */
.faq-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-width: 860px;
  margin: 0 auto;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color 0.2s ease;
}

.faq-item[open] {
  border-color: rgba(36, 231, 218, 0.45);
}

.faq-summary {
  padding: 20px 24px;
  font-weight: 700;
  font-size: 1.05rem;
  color: var(--text-primary);
  cursor: pointer;
  list-style: none;
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
}

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

.faq-summary::after {
  content: "+";
  font-size: 1.4rem;
  color: var(--accent-cyan);
  transition: transform 0.2s ease;
}

.faq-item[open] .faq-summary::after {
  content: "−";
  color: var(--accent-lime);
}

.faq-content {
  padding: 0 24px 20px 24px;
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.7;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
}

.faq-content a {
  color: var(--accent-cyan);
  text-decoration: underline;
  text-underline-offset: 4px;
}

/* Footer (Strictly 4 links) */
.site-footer {
  margin-top: auto;
  background: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 50px 0 30px 0;
}

.footer-nav {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 36px;
  list-style: none;
  margin-bottom: 24px;
  flex-wrap: wrap;
}

.footer-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 600;
  transition: color 0.2s ease;
}

.footer-link:hover {
  color: var(--accent-cyan);
}

.footer-copy {
  text-align: center;
  font-size: 0.85rem;
  color: var(--text-muted);
}

/* Article / Knowledge Styling */
.breadcrumbs {
  padding: 20px 0;
  font-size: 0.88rem;
  color: var(--text-muted);
}

.breadcrumbs a {
  color: var(--text-secondary);
  text-decoration: none;
}

.breadcrumbs a:hover {
  color: var(--accent-cyan);
}

.article-content {
  max-width: 840px;
  margin: 0 auto;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 48px;
}

.article-header {
  margin-bottom: 36px;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 24px;
}

.article-header h1 {
  font-size: 2.2rem;
  line-height: 1.3;
  margin-bottom: 16px;
  color: var(--text-primary);
}

.article-meta {
  display: flex;
  gap: 20px;
  color: var(--text-muted);
  font-size: 0.85rem;
}

.article-body {
  color: var(--text-secondary);
  font-size: 1.05rem;
  line-height: 1.8;
}

.article-body h2 {
  font-size: 1.5rem;
  color: var(--text-primary);
  margin: 36px 0 16px 0;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-color);
}

.article-body h3 {
  font-size: 1.2rem;
  color: var(--text-primary);
  margin: 24px 0 12px 0;
}

.article-body p {
  margin-bottom: 20px;
}

.article-body ul, .article-body ol {
  margin: 0 0 20px 24px;
}

.article-body li {
  margin-bottom: 8px;
}

.article-body a {
  color: var(--accent-cyan);
  text-decoration: underline;
  text-underline-offset: 4px;
}

.article-cta-box {
  background: var(--bg-secondary);
  border: 1px solid rgba(36, 231, 218, 0.35);
  border-radius: var(--radius-md);
  padding: 30px;
  text-align: center;
  margin: 40px 0;
}

/* Media Queries (Responsive 360, 390, 768, 1440) */
@media (max-width: 1024px) {
  .features-grid, .reviews-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  section {
    padding: 60px 0;
  }
  .hero-section {
    padding: 80px 0 60px 0;
    background-position: center center;
  }
  .hero-title {
    font-size: 2.2rem;
  }
  .hero-subtitle {
    font-size: 1.1rem;
  }
  .hero-stats {
    grid-template-columns: repeat(2, 1fr);
  }
  .features-grid, .stream-ai-grid, .reviews-grid {
    grid-template-columns: 1fr;
  }
  .nav-menu {
    gap: 16px;
  }
  .brand-logo-img {
    height: 32px;
  }
  .article-content {
    padding: 24px 18px;
  }
  .footer-nav {
    gap: 20px;
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: 1.85rem;
  }
  .hero-stats {
    grid-template-columns: 1fr;
    gap: 14px;
  }
  .btn {
    width: 100%;
  }
  .pricing-table .btn {
    width: auto;
    white-space: nowrap;
  }
  .hero-cta-group {
    flex-direction: column;
  }
  .footer-nav {
    flex-direction: column;
    gap: 14px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    animation: none !important;
  }
}