/* ==========================================================================
   寰宇云 (Huanyu Yun) 官方落地页样式表 - style.css
   规范：纯原生 CSS，零外部依赖，极速秒开，WCAG 2.1 AA 对比度合规
   ========================================================================== */

:root {
  --bg-primary: #0b0f19;
  --bg-secondary: #111827;
  --bg-card: #1f2937;
  --bg-card-hover: #283548;
  --text-primary: #f9fafb;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --accent-primary: #2563eb;
  --accent-hover: #1d4ed8;
  --accent-gradient: linear-gradient(135deg, #3b82f6 0%, #06b6d4 100%);
  --accent-glow: rgba(59, 130, 246, 0.25);
  --success: #10b981;
  --warning: #f59e0b;
  --border-color: #374151;
  --border-subtle: #1e293b;
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --max-width: 1200px;
  --header-height: 72px;
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --transition: all 0.25s ease-in-out;
}

/* 全局重置与无障碍基线 */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

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

body {
  font-family: var(--font-family);
  background-color: var(--bg-primary);
  background-image: 
    radial-gradient(rgba(56, 189, 248, 0.05) 1px, transparent 1px),
    radial-gradient(ellipse 80% 50% at 50% -20%, rgba(37, 99, 235, 0.12), transparent);
  background-size: 32px 32px, 100% 100%;
  color: var(--text-primary);
  line-height: 1.65;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* 键盘可访问跳转链接 (Skip Link) */
.skip-link {
  position: absolute;
  top: -100px;
  left: 1rem;
  background: var(--accent-primary);
  color: #ffffff;
  padding: 0.75rem 1.25rem;
  z-index: 9999;
  border-radius: var(--radius-sm);
  text-decoration: none;
  font-weight: 600;
  transition: top 0.2s ease;
}

.skip-link:focus {
  top: 1rem;
}

/* 焦点高亮 */
a:focus-visible, button:focus-visible, summary:focus-visible {
  outline: 2px solid #38bdf8;
  outline-offset: 3px;
}

/* 布局容器 */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.25rem;
}

/* 锚点防遮挡 */
section[id], h2[id], h3[id] {
  scroll-margin-top: calc(var(--header-height) + 1.5rem);
}

/* 页眉与导航 */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: rgba(11, 15, 25, 0.92);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  height: var(--header-height);
  display: flex;
  align-items: center;
}

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

.site-logo {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-primary);
  text-decoration: none;
  letter-spacing: -0.02em;
  transition: var(--transition);
}

.logo-icon {
  border-radius: 8px;
  transition: transform 0.25s ease, filter 0.25s ease;
  flex-shrink: 0;
}

.site-logo:hover .logo-icon {
  transform: scale(1.04);
  filter: drop-shadow(0 0 8px rgba(56, 189, 248, 0.45));
}

.logo-badge {
  background: var(--accent-gradient);
  color: #fff;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.15rem 0.5rem;
  border-radius: var(--radius-sm);
  text-transform: uppercase;
}

.main-nav {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 1.25rem;
  align-items: center;
  white-space: nowrap;
}

.nav-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  transition: var(--transition);
  padding: 0.4rem 0.2rem;
}

.nav-links a:hover, .nav-links a.active {
  color: #38bdf8;
}

.nav-cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  min-width: 44px;
  padding: 0.5rem 1.25rem;
  background: var(--accent-gradient);
  color: #ffffff;
  border-radius: var(--radius-md);
  font-weight: 600;
  font-size: 0.9rem;
  text-decoration: none;
  transition: var(--transition);
  box-shadow: 0 4px 14px var(--accent-glow);
}

.nav-cta:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(59, 130, 246, 0.4);
}

/* 按钮通用规范 (满足触控 >= 44x44px) */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
  min-width: 44px;
  padding: 0.75rem 1.75rem;
  border-radius: var(--radius-md);
  font-size: 1rem;
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: var(--transition);
  border: 1px solid transparent;
}

.btn-primary {
  position: relative;
  background: linear-gradient(135deg, #0284c7 0%, #2563eb 50%, #38bdf8 100%);
  background-size: 200% 200%;
  color: #ffffff;
  border: 1px solid rgba(56, 189, 248, 0.45);
  box-shadow: 0 4px 18px rgba(37, 99, 235, 0.35), 0 0 16px rgba(56, 189, 248, 0.2);
  animation: btnGradientShift 6s ease infinite;
  overflow: hidden;
}

@keyframes btnGradientShift {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

.btn-primary::after {
  content: "";
  position: absolute;
  top: -50%;
  left: -60%;
  width: 40%;
  height: 200%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.35), transparent);
  transform: rotate(30deg);
  pointer-events: none;
}

.btn-primary:hover::after {
  left: 140%;
  transition: left 0.75s ease-in-out;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(37, 99, 235, 0.5), 0 0 28px rgba(56, 189, 248, 0.4);
  border-color: #38bdf8;
}

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

.btn-secondary:hover {
  background-color: var(--bg-card-hover);
  border-color: #4b5563;
  color: #38bdf8;
}

.btn-block {
  width: 100%;
}

/* 主视觉区 (Hero) - 地球航线与航班穿梭背景图 */
.hero-section {
  padding: 6.5rem 0 5rem;
  text-align: center;
  position: relative;
  overflow: hidden;
  background-color: var(--bg-primary);
  background-image: 
    radial-gradient(circle at 50% 45%, rgba(11, 15, 25, 0.48) 0%, rgba(11, 15, 25, 0.85) 68%, var(--bg-primary) 100%),
    url('assets/flight-routes-globe.svg');
  background-position: center 35%;
  background-repeat: no-repeat;
  background-size: cover;
}

.hero-section::before {
  content: "";
  position: absolute;
  top: 15%;
  left: 50%;
  transform: translateX(-50%);
  width: min(800px, 92vw);
  height: 420px;
  background: radial-gradient(circle, rgba(56, 189, 248, 0.16) 0%, rgba(37, 99, 235, 0.08) 50%, transparent 75%);
  filter: blur(48px);
  pointer-events: none;
  z-index: 0;
}

.hero-section .container {
  position: relative;
  z-index: 1;
}

.hero-tag {
  display: inline-flex;
  align-items: center;
  gap: 0.65rem;
  padding: 0.45rem 1.25rem;
  background: rgba(15, 23, 42, 0.82);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(56, 189, 248, 0.45);
  border-radius: 9999px;
  font-size: 0.85rem;
  color: #38bdf8;
  margin-bottom: 1.5rem;
  font-weight: 600;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.4), 0 0 16px rgba(56, 189, 248, 0.18);
  transition: var(--transition);
}

.hero-tag:hover {
  border-color: #38bdf8;
  box-shadow: 0 4px 24px rgba(56, 189, 248, 0.35);
}

.live-status-dot {
  position: relative;
  width: 8px;
  height: 8px;
  background: #10b981;
  border-radius: 50%;
  box-shadow: 0 0 10px #10b981;
  flex-shrink: 0;
}

.live-status-dot::after {
  content: "";
  position: absolute;
  top: -4px;
  left: -4px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  border: 1.5px solid #10b981;
  animation: livePulse 2s cubic-bezier(0, 0.2, 0.8, 1) infinite;
}

@keyframes livePulse {
  0% { transform: scale(0.5); opacity: 1; }
  100% { transform: scale(2.4); opacity: 0; }
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3.25rem);
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 1.25rem;
  letter-spacing: -0.02em;
  text-shadow: 0 4px 24px rgba(0, 0, 0, 0.95);
}

.hero-title span {
  background: linear-gradient(135deg, #38bdf8 0%, #60a5fa 50%, #06b6d4 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  filter: drop-shadow(0 0 18px rgba(56, 189, 248, 0.3));
}

.hero-subtitle {
  font-size: clamp(1.05rem, 2.5vw, 1.25rem);
  color: #f1f5f9;
  max-width: 780px;
  margin: 0 auto 1.5rem;
  font-weight: 500;
  text-shadow: 0 2px 14px rgba(0, 0, 0, 0.9);
}

.hero-intro {
  font-size: 0.95rem;
  color: #cbd5e1;
  max-width: 680px;
  margin: 0 auto 2.5rem;
  text-shadow: 0 1px 8px rgba(0, 0, 0, 0.85);
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 1.25rem;
  flex-wrap: wrap;
  margin-bottom: 2.5rem;
}

/* 核心专网运行遥测指标 (HUD Stats Bar) */
.hero-hud-stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
  max-width: 860px;
  margin: 0 auto 2.75rem;
}

.hud-stat-item {
  background: rgba(15, 23, 42, 0.72);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid rgba(56, 189, 248, 0.22);
  border-radius: var(--radius-md);
  padding: 1.1rem 0.85rem;
  text-align: center;
  position: relative;
  overflow: hidden;
  transition: var(--transition);
}

.hud-stat-item::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent, #38bdf8, transparent);
  opacity: 0.8;
}

.hud-stat-item:hover {
  transform: translateY(-4px);
  border-color: rgba(56, 189, 248, 0.55);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.4), 0 0 20px rgba(56, 189, 248, 0.2);
  background: rgba(15, 23, 42, 0.9);
}

.hud-val {
  font-size: clamp(1.4rem, 2.5vw, 1.85rem);
  font-weight: 800;
  color: #f8fafc;
  line-height: 1.1;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, monospace;
  letter-spacing: -0.02em;
  text-shadow: 0 0 14px rgba(56, 189, 248, 0.4);
}

.hud-unit {
  font-size: 0.85rem;
  font-weight: 600;
  color: #38bdf8;
  margin-left: 2px;
}

.hud-label {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 0.35rem;
  font-weight: 500;
  letter-spacing: 0.02em;
}

.hero-guarantee {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 2rem;
  color: var(--text-muted);
  font-size: 0.875rem;
  flex-wrap: wrap;
}

.guarantee-item {
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.guarantee-item svg {
  color: var(--success);
}

/* 区块通用结构 */
.section-wrapper {
  padding: 4.5rem 0;
  border-top: 1px solid var(--border-subtle);
}

.section-header {
  text-align: center;
  max-width: 720px;
  margin: 0 auto 3rem;
}

.section-tag {
  color: #38bdf8;
  font-size: 0.85rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 0.5rem;
  display: block;
}

.section-title {
  font-size: clamp(1.75rem, 3.5vw, 2.25rem);
  font-weight: 700;
  margin-bottom: 0.75rem;
  color: var(--text-primary);
}

.section-desc {
  font-size: 1rem;
  color: var(--text-secondary);
}

/* 核心优势卡片 (3列) */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

.feature-card {
  position: relative;
  background: rgba(31, 41, 55, 0.7);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid rgba(55, 65, 81, 0.85);
  border-radius: var(--radius-lg);
  padding: 2.25rem 2rem;
  transition: var(--transition);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.feature-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 36px;
  height: 2.5px;
  background: linear-gradient(90deg, #38bdf8, #2563eb);
  transition: width 0.35s ease;
}

.feature-card:hover {
  transform: translateY(-6px);
  border-color: rgba(56, 189, 248, 0.5);
  box-shadow: 0 16px 36px rgba(0, 0, 0, 0.45), 0 0 24px rgba(56, 189, 248, 0.18);
  background: rgba(31, 41, 55, 0.95);
}

.feature-card:hover::before {
  width: 100%;
}

.feature-icon-wrapper {
  width: 56px;
  height: 56px;
  border-radius: var(--radius-md);
  background: rgba(37, 99, 235, 0.18);
  color: #38bdf8;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.5rem;
  border: 1px solid rgba(56, 189, 248, 0.3);
  box-shadow: 0 0 16px rgba(56, 189, 248, 0.15);
  transition: var(--transition);
}

.feature-card:hover .feature-icon-wrapper {
  transform: scale(1.08);
  background: rgba(37, 99, 235, 0.28);
  border-color: #38bdf8;
  box-shadow: 0 0 22px rgba(56, 189, 248, 0.35);
}

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

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

/* 流媒体与 AI 支持图卡 */
.media-ai-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
}

.media-ai-card {
  position: relative;
  background: rgba(31, 41, 55, 0.7);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid rgba(55, 65, 81, 0.85);
  border-radius: var(--radius-lg);
  padding: 2.25rem;
  transition: var(--transition);
  overflow: hidden;
}

.media-ai-card:hover {
  transform: translateY(-4px);
  border-color: rgba(56, 189, 248, 0.45);
  box-shadow: 0 16px 36px rgba(0, 0, 0, 0.4), 0 0 20px rgba(56, 189, 248, 0.12);
}

.media-ai-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.25rem;
}

.media-ai-header h3 {
  font-size: 1.25rem;
  font-weight: 700;
}

.badge-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin-top: 1.25rem;
}

.service-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background-color: rgba(17, 24, 39, 0.85);
  border: 1px solid rgba(55, 65, 81, 0.9);
  padding: 0.45rem 0.9rem;
  border-radius: 9999px;
  font-size: 0.85rem;
  color: var(--text-secondary);
  font-weight: 500;
  transition: var(--transition);
}

.service-pill:hover {
  border-color: #38bdf8;
  color: #ffffff;
  background-color: rgba(37, 99, 235, 0.2);
  transform: translateY(-1px);
  box-shadow: 0 2px 8px rgba(56, 189, 248, 0.2);
}

.service-pill.highlight {
  border-color: rgba(56, 189, 248, 0.5);
  color: #38bdf8;
  background-color: rgba(37, 99, 235, 0.18);
  font-weight: 600;
}

/* 套餐价格对比表 */
.pricing-wrapper {
  margin-top: 1.5rem;
}

.table-responsive {
  width: 100%;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  background-color: var(--bg-card);
}

.pricing-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  font-size: 0.95rem;
}

.pricing-table caption {
  font-size: 0.85rem;
  color: var(--text-muted);
  padding: 0.75rem 1rem;
  text-align: left;
  background: var(--bg-secondary);
  border-bottom: 1px solid var(--border-color);
}

.pricing-table th, .pricing-table td {
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--border-color);
}

.pricing-table th {
  background-color: var(--bg-secondary);
  font-weight: 700;
  color: var(--text-primary);
  white-space: nowrap;
}

.pricing-table tbody tr:hover {
  background-color: rgba(56, 189, 248, 0.08);
}

.pricing-table tbody tr.popular-row {
  background: rgba(37, 99, 235, 0.12);
}

.pricing-table tbody tr.popular-row td:first-child {
  border-left: 3px solid #38bdf8;
}

.plan-name {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text-primary);
  display: block;
}

.plan-tag {
  display: inline-block;
  font-size: 0.75rem;
  padding: 0.2rem 0.55rem;
  background: rgba(37, 99, 235, 0.2);
  color: #60a5fa;
  border-radius: var(--radius-sm);
  margin-top: 0.25rem;
}

.plan-tag.hot {
  background: linear-gradient(135deg, rgba(245, 158, 11, 0.25) 0%, rgba(239, 68, 68, 0.25) 100%);
  color: #fde047;
  border: 1px solid rgba(245, 158, 11, 0.45);
  box-shadow: 0 0 10px rgba(245, 158, 11, 0.25);
  animation: hotGlow 3s ease-in-out infinite alternate;
}

@keyframes hotGlow {
  0% { border-color: rgba(245, 158, 11, 0.35); }
  100% { border-color: rgba(245, 158, 11, 0.85); box-shadow: 0 0 14px rgba(245, 158, 11, 0.45); }
}

.price-val {
  font-size: 1.4rem;
  font-weight: 800;
  color: #38bdf8;
}

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

/* 用户评价 */
.reviews-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

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

.review-stars {
  color: #f59e0b;
  font-size: 1rem;
  margin-bottom: 0.75rem;
  letter-spacing: 2px;
}

.review-text {
  font-size: 0.95rem;
  color: var(--text-secondary);
  margin-bottom: 1.25rem;
  font-style: italic;
}

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

.author-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--accent-gradient);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  color: #ffffff;
  font-size: 0.9rem;
}

.author-info h4 {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-primary);
}

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

/* 常见问题 (FAQ) - 默认展开 */
.faq-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  max-width: 860px;
  margin: 0 auto;
}

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

.faq-item[open] {
  border-color: rgba(59, 130, 246, 0.4);
}

.faq-question {
  padding: 1.25rem 1.5rem;
  font-size: 1.05rem;
  font-weight: 600;
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  color: var(--text-primary);
  user-select: none;
}

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

.faq-question::after {
  content: "−";
  font-size: 1.4rem;
  font-weight: 700;
  color: #38bdf8;
  margin-left: 1rem;
  line-height: 1;
}

.faq-item:not([open]) .faq-question::after {
  content: "+";
}

.faq-answer {
  padding: 0 1.5rem 1.25rem;
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.7;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  margin-top: 0.25rem;
  padding-top: 0.75rem;
}

.faq-answer a {
  color: #38bdf8;
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* 底部页脚 (严格只保留四个标题) */
.site-footer {
  margin-top: auto;
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border-color);
  padding: 3rem 0 2rem;
  font-size: 0.95rem;
}

.footer-nav {
  display: flex;
  justify-content: center;
  gap: 2.5rem;
  margin-bottom: 1.75rem;
  flex-wrap: wrap;
}

.footer-nav a {
  color: var(--text-secondary);
  text-decoration: none;
  font-weight: 600;
  font-size: 1rem;
  transition: var(--transition);
  padding: 0.5rem;
}

.footer-nav a:hover {
  color: #38bdf8;
}

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

/* 文章与子页面专用样式 */
.article-header {
  padding: 3.5rem 0 2rem;
  text-align: center;
  border-bottom: 1px solid var(--border-subtle);
}

.breadcrumb-nav {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-bottom: 1.25rem;
}

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

.breadcrumb-nav a:hover {
  color: #38bdf8;
}

.article-content {
  max-width: 820px;
  margin: 3rem auto;
  font-size: 1.05rem;
  line-height: 1.85;
  color: var(--text-secondary);
}

.article-content h2 {
  color: var(--text-primary);
  font-size: 1.6rem;
  font-weight: 700;
  margin: 2.5rem 0 1rem;
  border-left: 4px solid #3b82f6;
  padding-left: 0.75rem;
}

.article-content h3 {
  color: var(--text-primary);
  font-size: 1.3rem;
  font-weight: 600;
  margin: 1.75rem 0 0.75rem;
}

.article-content p {
  margin-bottom: 1.25rem;
}

.article-content ul, .article-content ol {
  margin: 1rem 0 1.5rem 1.5rem;
}

.article-content li {
  margin-bottom: 0.5rem;
}

.article-content a {
  color: #38bdf8;
  text-decoration: underline;
  text-underline-offset: 3px;
}

.article-cta-box {
  background: linear-gradient(135deg, rgba(37, 99, 235, 0.15) 0%, rgba(6, 182, 212, 0.15) 100%);
  border: 1px solid rgba(59, 130, 246, 0.4);
  border-radius: var(--radius-lg);
  padding: 2rem;
  text-align: center;
  margin: 3rem 0;
}

.article-meta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.5rem;
  color: var(--text-muted);
  font-size: 0.875rem;
  margin-top: 1rem;
}

/* 知识科普专区索引页卡片 */
.articles-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.75rem;
  margin-top: 2rem;
}

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

.article-card:hover {
  transform: translateY(-4px);
  border-color: #38bdf8;
  box-shadow: 0 12px 28px rgba(0,0,0,0.4);
}

.article-card-tag {
  font-size: 0.75rem;
  color: #38bdf8;
  font-weight: 700;
  text-transform: uppercase;
  margin-bottom: 0.5rem;
}

.article-card-title {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: 0.75rem;
  line-height: 1.4;
}

.article-card-excerpt {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: 1.25rem;
}

.article-card-link {
  color: #38bdf8;
  text-decoration: none;
  font-weight: 600;
  font-size: 0.9rem;
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
}

.article-card-link:hover {
  text-decoration: underline;
}

/* ==========================================================================
   响应式媒体查询 (@media) - 完美适配 360px, 390px, 768px, 1440px
   ========================================================================== */

/* 平板与窄屏桌面 (<= 1024px) */
@media (max-width: 1024px) {
  .features-grid {
    grid-template-columns: 1fr;
    max-width: 680px;
    margin: 0 auto;
  }
  .media-ai-grid {
    grid-template-columns: 1fr;
  }
  .reviews-grid {
    grid-template-columns: 1fr;
    max-width: 680px;
    margin: 0 auto;
  }
  .articles-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

/* 移动端横向与平板小尺寸 (<= 768px) */
@media (max-width: 768px) {
  .site-header {
    height: auto;
    padding: 0.75rem 0;
  }
  .header-inner {
    flex-wrap: wrap;
    gap: 0.75rem;
  }
  .main-nav {
    width: 100%;
    justify-content: space-between;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    padding-bottom: 0.35rem;
    scrollbar-width: none;
  }
  .main-nav::-webkit-scrollbar {
    display: none;
  }
  .nav-links {
    gap: 1.1rem;
    font-size: 0.875rem;
    white-space: nowrap;
  }
  .hero-section {
    padding: 3rem 0 2.5rem;
  }
  .hero-actions {
    flex-direction: column;
    align-items: stretch;
    max-width: 340px;
    margin-left: auto;
    margin-right: auto;
  }
  .hero-hud-stats {
    grid-template-columns: repeat(2, 1fr);
    gap: 0.75rem;
    margin-bottom: 2rem;
  }
  .btn {
    width: 100%;
  }
  .articles-grid {
    grid-template-columns: 1fr;
  }
  .footer-nav {
    flex-direction: column;
    align-items: center;
    gap: 1rem;
  }
}

/* 移动端手机标准屏与微屏 (<= 390px, 360px) */
@media (max-width: 390px) {
  html {
    font-size: 15px;
  }
  .container {
    padding: 0 0.85rem;
  }
  .hero-title {
    font-size: 1.85rem;
  }
  .hero-hud-stats {
    grid-template-columns: 1fr 1fr;
    gap: 0.5rem;
  }
  .hud-stat-item {
    padding: 0.75rem 0.45rem;
  }
  .hud-val {
    font-size: 1.3rem;
  }
  .hud-label {
    font-size: 0.72rem;
  }
  .feature-card, .media-ai-card, .review-card, .article-card {
    padding: 1.25rem;
  }
  .pricing-table th, .pricing-table td {
    padding: 1rem 0.75rem;
  }
  .faq-question {
    padding: 1rem;
    font-size: 0.95rem;
  }
  .faq-answer {
    padding: 0 1rem 1rem;
  }
}

/* 用户偏好减少动画 */
@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;
  }
}