/* ==========================================================================
   云图机场 (Yuntu Accelerator) - 极简高性能原生样式表 (深色科技质感排版)
   零外部依赖 | 秒开加载 | 响应式自适应 | 无障碍优化 (WCAG 2.1 AA)
   ========================================================================== */

:root {
  --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;

  /* 深色科技色彩系统 (Dark Cyber Palette) */
  --color-bg: #070b14;
  --color-bg-alt: #0c1322;
  --color-surface: #0f182c;
  --color-surface-hover: #16223d;
  --color-surface-glass: rgba(15, 24, 44, 0.75);
  --color-surface-elevated: #152038;

  --color-text-main: #f8fafc;
  --color-text-muted: #94a3b8;
  --color-text-light: #64748b;

  --color-primary: #38bdf8;
  --color-primary-hover: #7dd3fc;
  --color-primary-dark: #0284c7;
  --color-primary-light: rgba(56, 189, 248, 0.12);
  --color-primary-border: rgba(56, 189, 248, 0.35);

  --color-accent: #6366f1;
  --color-accent-gradient: linear-gradient(135deg, #38bdf8 0%, #2563eb 50%, #8b5cf6 100%);
  --color-card-gradient: linear-gradient(180deg, rgba(30, 41, 59, 0.6) 0%, rgba(15, 24, 44, 0.8) 100%);
  --color-btn-gradient: linear-gradient(135deg, #2563eb 0%, #0284c7 100%);
  --color-btn-gradient-hover: linear-gradient(135deg, #3b82f6 0%, #38bdf8 100%);

  --color-border: rgba(255, 255, 255, 0.08);
  --color-border-dark: rgba(255, 255, 255, 0.15);
  --color-success: #10b981;
  --color-warning: #f59e0b;

  --color-tag: rgba(56, 189, 248, 0.1);
  --color-tag-text: #38bdf8;

  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.4);
  --shadow-md: 0 4px 12px -2px rgba(0, 0, 0, 0.5), 0 2px 4px -2px rgba(0, 0, 0, 0.4);
  --shadow-lg: 0 12px 24px -4px rgba(0, 0, 0, 0.6), 0 4px 8px -4px rgba(0, 0, 0, 0.4);
  --glow-primary: 0 0 25px rgba(56, 189, 248, 0.25);
  --glow-accent: 0 0 30px rgba(99, 102, 241, 0.2);

  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-full: 9999px;

  --max-width: 1200px;
  --header-height: 72px;
}

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

html {
  font-family: var(--font-family);
  font-size: 16px;
  line-height: 1.65;
  color: var(--color-text-main);
  background-color: var(--color-bg);
  background-image: radial-gradient(ellipse 90% 60% at 50% -15%, rgba(37, 99, 235, 0.2) 0%, transparent 75%);
  background-attachment: fixed;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background-color: transparent;
}

/* 跳转至主要内容 (Accessibility Skip Link) */
.skip-link {
  position: absolute;
  top: -100px;
  left: 1rem;
  background: var(--color-primary);
  color: #070b14;
  padding: 0.75rem 1.25rem;
  z-index: 9999;
  border-radius: var(--radius-sm);
  text-decoration: none;
  font-weight: 700;
  transition: top 0.2s ease;
}
.skip-link:focus {
  top: 1rem;
  outline: 3px solid #ffffff;
}

/* 锚点防遮挡 */
h1, h2, h3, h4, h5, h6, section[id] {
  scroll-margin-top: calc(var(--header-height) + 1.5rem);
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color 0.15s ease, border-color 0.15s ease;
}
a:hover {
  color: var(--color-primary-hover);
  text-decoration: underline;
}
a:focus-visible, button:focus-visible, summary:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
}

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

/* 容器规范 */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: 1.5rem;
  padding-right: 1.5rem;
}

/* 页眉与导航 */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--header-height);
  background-color: rgba(7, 11, 20, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--color-border);
}
.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 100%;
}
.brand-logo {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--color-text-main);
  text-decoration: none;
  letter-spacing: -0.02em;
}
.brand-logo svg {
  width: 30px;
  height: 30px;
  fill: var(--color-primary);
  filter: drop-shadow(0 0 8px rgba(56, 189, 248, 0.5));
}
.site-nav {
  display: flex;
  align-items: center;
  gap: 1.75rem;
}
.nav-link {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--color-text-muted);
  text-decoration: none;
  padding: 0.5rem 0.25rem;
  position: relative;
  transition: color 0.2s ease;
}
.nav-link:hover {
  color: var(--color-primary);
  text-decoration: none;
}
.nav-link.active {
  color: var(--color-primary);
  font-weight: 600;
}
.nav-link.active::after {
  content: "";
  position: absolute;
  bottom: 0;
  left: 0.25rem;
  right: 0.25rem;
  height: 2px;
  background: var(--color-primary);
  border-radius: var(--radius-full);
  box-shadow: 0 0 8px var(--color-primary);
}

/* 按钮规范 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 0.95rem;
  font-weight: 600;
  line-height: 1;
  padding: 0.75rem 1.4rem;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  text-decoration: none;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  min-height: 44px;
  min-width: 44px;
}
.btn-primary {
  background: var(--color-btn-gradient);
  color: #ffffff;
  border: 1px solid rgba(255, 255, 255, 0.15);
  box-shadow: 0 0 16px rgba(37, 99, 235, 0.35);
}
.btn-primary:hover {
  background: var(--color-btn-gradient-hover);
  color: #ffffff;
  box-shadow: 0 0 24px rgba(56, 189, 248, 0.55);
  transform: translateY(-1px);
  text-decoration: none;
}
.btn-outline {
  background-color: rgba(255, 255, 255, 0.03);
  color: var(--color-text-main);
  border-color: rgba(255, 255, 255, 0.18);
  backdrop-filter: blur(6px);
}
.btn-outline:hover {
  background-color: rgba(56, 189, 248, 0.1);
  border-color: var(--color-primary);
  color: var(--color-primary);
  transform: translateY(-1px);
  text-decoration: none;
}
.btn-lg {
  min-height: 50px;
  padding: 0.85rem 1.85rem;
  font-size: 1.05rem;
  border-radius: var(--radius-md);
}
.btn-block {
  width: 100%;
}

/* ==========================================================================
   主视觉区 (Hero Section - 科技双栏排版)
   ========================================================================== */

.hero-section {
  padding: 5rem 0 4.5rem;
  position: relative;
  overflow: hidden;
}
.hero-container {
  display: grid;
  grid-template-columns: 1.15fr 0.85fr;
  align-items: center;
  gap: 3.5rem;
}
.hero-content {
  text-align: left;
}
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.4rem 1rem;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-primary);
  background: rgba(56, 189, 248, 0.08);
  border: 1px solid rgba(56, 189, 248, 0.25);
  border-radius: var(--radius-full);
  margin-bottom: 1.5rem;
  box-shadow: 0 0 15px rgba(56, 189, 248, 0.15);
}
.badge-pulse {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: #10b981;
  box-shadow: 0 0 10px #10b981;
  animation: pulse-glow 2s infinite;
}
@keyframes pulse-glow {
  0% { transform: scale(0.95); box-shadow: 0 0 0 0 rgba(16, 185, 129, 0.7); }
  70% { transform: scale(1.05); box-shadow: 0 0 0 8px rgba(16, 185, 129, 0); }
  100% { transform: scale(0.95); box-shadow: 0 0 0 0 rgba(16, 185, 129, 0); }
}

.hero-title {
  font-size: 2.85rem;
  line-height: 1.22;
  font-weight: 800;
  color: var(--color-text-main);
  letter-spacing: -0.03em;
  margin-bottom: 1.25rem;
}
.text-gradient {
  background: var(--color-accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  display: inline-block;
}
.hero-subtitle {
  font-size: 1.2rem;
  color: #cbd5e1;
  margin-bottom: 1.25rem;
  font-weight: 400;
  line-height: 1.6;
}
.hero-intro {
  font-size: 0.98rem;
  color: var(--color-text-muted);
  margin-bottom: 2rem;
  line-height: 1.75;
}
.hero-cta {
  display: flex;
  align-items: center;
  gap: 1.25rem;
  margin-bottom: 2.25rem;
  flex-wrap: wrap;
}
.hero-trust {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  font-size: 0.875rem;
  color: var(--color-text-muted);
  flex-wrap: wrap;
}
.hero-trust span {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  background: rgba(255, 255, 255, 0.03);
  padding: 0.35rem 0.75rem;
  border-radius: var(--radius-sm);
  border: 1px solid rgba(255, 255, 255, 0.05);
}
.hero-trust svg {
  width: 16px;
  height: 16px;
  fill: var(--color-success);
}

/* 科技监控看板 (Hero Live Network Monitor Visual) */
.hero-visual {
  display: flex;
  justify-content: center;
}
.monitor-card {
  width: 100%;
  max-width: 480px;
  background: rgba(15, 24, 44, 0.85);
  border: 1px solid rgba(56, 189, 248, 0.25);
  border-radius: var(--radius-lg);
  box-shadow: 0 20px 40px -10px rgba(0, 0, 0, 0.7), 0 0 30px rgba(56, 189, 248, 0.15);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  overflow: hidden;
}
.monitor-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.85rem 1.25rem;
  background: rgba(7, 11, 20, 0.6);
  border-bottom: 1px solid var(--color-border);
}
.monitor-dots {
  display: flex;
  gap: 6px;
}
.dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
}
.dot-red { background-color: #ef4444; }
.dot-yellow { background-color: #f59e0b; }
.dot-green { background-color: #10b981; }
.monitor-title {
  font-size: 0.825rem;
  font-weight: 600;
  color: var(--color-text-muted);
  letter-spacing: 0.02em;
}
.monitor-status {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.75rem;
  font-weight: 600;
  color: #10b981;
}
.status-indicator {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background-color: #10b981;
  box-shadow: 0 0 8px #10b981;
}
.monitor-body {
  padding: 1rem 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}
.node-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.75rem 1rem;
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid rgba(255, 255, 255, 0.05);
  border-radius: var(--radius-sm);
  transition: all 0.2s ease;
}
.node-row:hover {
  background: rgba(56, 189, 248, 0.06);
  border-color: rgba(56, 189, 248, 0.3);
}
.node-info {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}
.node-flag {
  font-size: 1.25rem;
}
.node-text {
  display: flex;
  flex-direction: column;
}
.node-name {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--color-text-main);
}
.node-meta {
  font-size: 0.75rem;
  color: var(--color-text-light);
}
.node-stats {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  font-family: var(--font-mono);
}
.stat-ping {
  font-size: 0.85rem;
  font-weight: 700;
  color: #10b981;
}
.stat-loss {
  font-size: 0.75rem;
  color: var(--color-text-light);
}
.monitor-footer {
  padding: 0.85rem 1.25rem;
  background: rgba(7, 11, 20, 0.4);
  border-top: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.monitor-gauge {
  font-size: 0.825rem;
  color: var(--color-text-muted);
}
.gauge-value {
  font-family: var(--font-mono);
  font-weight: 700;
  color: var(--color-primary);
  margin-left: 0.25rem;
}
.monitor-tag {
  font-size: 0.75rem;
  font-weight: 600;
  color: #38bdf8;
  background: rgba(56, 189, 248, 0.1);
  padding: 0.25rem 0.6rem;
  border-radius: var(--radius-sm);
  border: 1px solid rgba(56, 189, 248, 0.2);
}

/* ==========================================================================
   区块公用规范
   ========================================================================== */

.section {
  padding: 5rem 0;
  position: relative;
}
.section-alt {
  background-color: var(--color-bg-alt);
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
}
.section-header {
  text-align: center;
  max-width: 720px;
  margin: 0 auto 3.5rem;
}
.section-tag {
  font-size: 0.825rem;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--color-primary);
  letter-spacing: 0.08em;
  margin-bottom: 0.75rem;
  display: inline-block;
  background: rgba(56, 189, 248, 0.1);
  padding: 0.25rem 0.85rem;
  border-radius: var(--radius-full);
  border: 1px solid rgba(56, 189, 248, 0.2);
}
.section-title {
  font-size: 2.15rem;
  font-weight: 800;
  color: var(--color-text-main);
  line-height: 1.3;
  margin-bottom: 0.85rem;
  letter-spacing: -0.02em;
}
.section-desc {
  font-size: 1.05rem;
  color: var(--color-text-muted);
  line-height: 1.65;
}

/* ==========================================================================
   核心优势卡片网格 (3图文卡片)
   ========================================================================== */

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.75rem;
}
.feature-card {
  background: var(--color-card-gradient);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 2.25rem;
  position: relative;
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
  backdrop-filter: blur(8px);
}
.feature-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent, rgba(56, 189, 248, 0.4), transparent);
  border-radius: var(--radius-md) var(--radius-md) 0 0;
  opacity: 0;
  transition: opacity 0.25s ease;
}
.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 30px -5px rgba(0, 0, 0, 0.6), var(--glow-primary);
  border-color: var(--color-primary-border);
}
.feature-card:hover::before {
  opacity: 1;
}
.feature-icon-wrapper {
  width: 52px;
  height: 52px;
  border-radius: var(--radius-md);
  background: rgba(56, 189, 248, 0.12);
  border: 1px solid rgba(56, 189, 248, 0.25);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 1.5rem;
  box-shadow: 0 0 15px rgba(56, 189, 248, 0.2);
}
.feature-icon-wrapper svg {
  width: 26px;
  height: 26px;
  fill: var(--color-primary);
}
.feature-title {
  font-size: 1.3rem;
  font-weight: 700;
  margin-bottom: 0.85rem;
  color: var(--color-text-main);
  letter-spacing: -0.01em;
}
.feature-text {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  line-height: 1.7;
}

/* ==========================================================================
   流媒体与AI支持卡片网格
   ========================================================================== */

.media-ai-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 2rem;
}
.media-card {
  background: var(--color-card-gradient);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 2.25rem;
  backdrop-filter: blur(8px);
  transition: border-color 0.2s ease, transform 0.2s ease;
}
.media-card:hover {
  border-color: var(--color-primary-border);
  transform: translateY(-2px);
}
.media-header {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-bottom: 1.25rem;
}
.media-header svg {
  width: 32px;
  height: 32px;
  fill: var(--color-primary);
  filter: drop-shadow(0 0 8px rgba(56, 189, 248, 0.4));
}
.media-title {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--color-text-main);
}
.media-desc {
  font-size: 0.98rem;
  color: var(--color-text-muted);
  margin-bottom: 1.75rem;
  line-height: 1.65;
}
.tags-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
}
.tag-badge {
  display: inline-flex;
  align-items: center;
  padding: 0.45rem 0.85rem;
  font-size: 0.85rem;
  font-weight: 600;
  background: rgba(255, 255, 255, 0.04);
  color: #e2e8f0;
  border-radius: var(--radius-sm);
  border: 1px solid rgba(255, 255, 255, 0.1);
  transition: all 0.2s ease;
}
.tag-badge:hover {
  background: rgba(56, 189, 248, 0.15);
  border-color: var(--color-primary);
  color: var(--color-primary);
  transform: translateY(-1px);
}

/* ==========================================================================
   套餐价格对比表
   ========================================================================== */

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1.5rem;
  margin-bottom: 2.5rem;
}
.pricing-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: 2.25rem 1.75rem;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}
.pricing-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: rgba(255, 255, 255, 0.2);
}
.pricing-card.featured {
  background: linear-gradient(180deg, #15223e 0%, #0d172c 100%);
  border: 2px solid var(--color-primary);
  box-shadow: 0 0 35px rgba(56, 189, 248, 0.25), var(--shadow-lg);
}
.pricing-badge {
  position: absolute;
  top: -13px;
  left: 50%;
  transform: translateX(-50%);
  background: linear-gradient(135deg, #2563eb, #38bdf8);
  color: #ffffff;
  font-size: 0.775rem;
  font-weight: 700;
  padding: 0.3rem 0.95rem;
  border-radius: var(--radius-full);
  white-space: nowrap;
  box-shadow: 0 0 12px rgba(56, 189, 248, 0.5);
  letter-spacing: 0.02em;
}
.pricing-name {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-text-main);
  margin-bottom: 0.5rem;
}
.pricing-desc {
  font-size: 0.875rem;
  color: var(--color-text-light);
  min-height: 2.5rem;
  margin-bottom: 1.25rem;
  line-height: 1.5;
}
.pricing-price {
  display: flex;
  align-items: baseline;
  gap: 0.35rem;
  margin-bottom: 1.75rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--color-border);
}
.price-symbol {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--color-primary);
}
.price-number {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--color-text-main);
  line-height: 1;
  letter-spacing: -0.02em;
}
.price-unit {
  font-size: 0.9rem;
  color: var(--color-text-muted);
}
.pricing-features {
  list-style: none;
  margin: 0 0 2rem;
  flex-grow: 1;
}
.pricing-features li {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  font-size: 0.925rem;
  color: #cbd5e1;
  margin-bottom: 0.85rem;
  line-height: 1.45;
}
.pricing-features svg {
  width: 17px;
  height: 17px;
  fill: var(--color-success);
  flex-shrink: 0;
  filter: drop-shadow(0 0 4px rgba(16, 185, 129, 0.4));
}

/* ==========================================================================
   用户真实评价
   ========================================================================== */

.reviews-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.75rem;
}
.review-card {
  background: var(--color-card-gradient);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 2rem;
  backdrop-filter: blur(8px);
  transition: transform 0.25s ease, border-color 0.25s ease, box-shadow 0.25s ease;
  display: flex;
  flex-direction: column;
}
.review-card:hover {
  transform: translateY(-3px);
  border-color: rgba(56, 189, 248, 0.35);
  box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.5), var(--glow-primary);
}
.review-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.25rem;
  flex-wrap: wrap;
  gap: 0.5rem;
}
.review-rating {
  display: flex;
  gap: 0.25rem;
  color: #f59e0b;
}
.review-rating svg {
  width: 17px;
  height: 17px;
  fill: currentColor;
}
.review-verified {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.75rem;
  font-weight: 600;
  color: #10b981;
  background: rgba(16, 185, 129, 0.1);
  padding: 0.2rem 0.55rem;
  border-radius: var(--radius-sm);
  border: 1px solid rgba(16, 185, 129, 0.2);
}
.review-verified svg {
  width: 13px;
  height: 13px;
  fill: currentColor;
}
.review-text {
  font-size: 0.95rem;
  color: #cbd5e1;
  line-height: 1.75;
  margin-bottom: 1.75rem;
  font-style: normal;
  flex-grow: 1;
}
.review-user {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  padding-top: 1rem;
  border-top: 1px solid rgba(255, 255, 255, 0.06);
}
.user-avatar {
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: linear-gradient(135deg, rgba(56, 189, 248, 0.2), rgba(99, 102, 241, 0.2));
  border: 1px solid rgba(56, 189, 248, 0.3);
  color: var(--color-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.05rem;
}
.user-info {
  display: flex;
  flex-direction: column;
}
.user-name {
  font-size: 0.925rem;
  font-weight: 600;
  color: var(--color-text-main);
}
.user-meta {
  font-size: 0.8rem;
  color: var(--color-text-light);
}

/* ==========================================================================
   FAQ 常见问题 (默认展开 <details open>)
   ========================================================================== */

.faq-list {
  max-width: 860px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
}
.faq-item {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
.faq-item:hover, .faq-item[open] {
  border-color: rgba(56, 189, 248, 0.3);
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
}
.faq-summary {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--color-text-main);
  padding: 1.35rem 1.75rem;
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  user-select: none;
  transition: color 0.15s ease;
}
.faq-summary:hover {
  color: var(--color-primary);
}
.faq-summary::-webkit-details-marker {
  display: none;
}
.faq-summary::after {
  content: "▾";
  font-size: 1.35rem;
  color: var(--color-primary);
  transition: transform 0.25s ease;
}
.faq-item[open] .faq-summary::after {
  transform: rotate(180deg);
}
.faq-answer {
  padding: 0 1.75rem 1.5rem;
  font-size: 0.98rem;
  color: #cbd5e1;
  line-height: 1.75;
  border-top: 1px solid rgba(255, 255, 255, 0.05);
  margin-top: 0.25rem;
  padding-top: 1.25rem;
}
.faq-answer p:not(:last-child) {
  margin-bottom: 0.85rem;
}

/* ==========================================================================
   页脚 (严格保留四个标题外链)
   ========================================================================== */

.site-footer {
  background-color: #05080f;
  color: #94a3b8;
  padding: 4rem 0 2.5rem;
  margin-top: auto;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}
.footer-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 2rem;
  padding-bottom: 2.5rem;
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
}
.footer-brand {
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}
.footer-logo {
  font-size: 1.35rem;
  font-weight: 800;
  color: #f8fafc;
  display: flex;
  align-items: center;
  gap: 0.65rem;
}
.footer-logo svg {
  width: 26px;
  height: 26px;
  fill: var(--color-primary);
  filter: drop-shadow(0 0 6px rgba(56, 189, 248, 0.4));
}
.footer-slogan {
  font-size: 0.9rem;
  color: var(--color-text-light);
}
.footer-nav {
  display: flex;
  align-items: center;
  gap: 2.25rem;
  flex-wrap: wrap;
}
.footer-link {
  color: #cbd5e1;
  font-size: 0.98rem;
  font-weight: 500;
  text-decoration: none;
  padding: 0.5rem 0;
  transition: color 0.15s ease;
}
.footer-link:hover {
  color: var(--color-primary);
  text-decoration: underline;
}
.footer-bottom {
  padding-top: 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
  font-size: 0.85rem;
  color: var(--color-text-light);
}

/* ==========================================================================
   文章详情页 / 知识科普页专用样式
   ========================================================================== */

.article-header {
  padding: 3.5rem 0 2.5rem;
  background-color: var(--color-bg-alt);
  border-bottom: 1px solid var(--color-border);
  text-align: center;
}
.article-header h1 {
  font-size: 2.2rem;
  font-weight: 800;
  color: var(--color-text-main);
  letter-spacing: -0.02em;
}
.article-meta {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.5rem;
  font-size: 0.875rem;
  color: var(--color-text-muted);
  margin-top: 1rem;
  flex-wrap: wrap;
}
.article-content {
  max-width: 860px;
  margin: 3.5rem auto;
  background: var(--color-surface);
  padding: 2.75rem 3.25rem;
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-md);
}
.article-content h1 {
  font-size: 2rem;
  font-weight: 800;
  color: var(--color-text-main);
  margin-bottom: 1.25rem;
  line-height: 1.35;
}
.article-content h2 {
  font-size: 1.55rem;
  font-weight: 700;
  color: var(--color-text-main);
  margin: 2.5rem 0 1.25rem;
  padding-bottom: 0.65rem;
  border-bottom: 1px solid var(--color-border);
}
.article-content h3 {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--color-text-main);
  margin: 1.75rem 0 0.85rem;
}
.article-content p {
  font-size: 1.025rem;
  line-height: 1.85;
  color: #cbd5e1;
  margin-bottom: 1.35rem;
}
.article-content ul, .article-content ol {
  padding-left: 1.75rem;
  margin-bottom: 1.35rem;
  color: #cbd5e1;
}
.article-content li {
  margin-bottom: 0.65rem;
  line-height: 1.75;
}
.article-content blockquote {
  background-color: rgba(56, 189, 248, 0.05);
  border-left: 4px solid var(--color-primary);
  padding: 1.25rem 1.5rem;
  margin: 1.75rem 0;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  color: #94a3b8;
}
.article-cta-box {
  background: linear-gradient(135deg, rgba(37, 99, 235, 0.15) 0%, rgba(56, 189, 248, 0.08) 100%);
  border: 1px solid var(--color-primary-border);
  border-radius: var(--radius-md);
  padding: 2rem;
  text-align: center;
  margin: 2.75rem 0;
  box-shadow: 0 0 20px rgba(56, 189, 248, 0.1);
}
.article-cta-box h3 {
  margin-top: 0;
  font-size: 1.35rem;
  color: var(--color-text-main);
}
.article-cta-box p {
  color: var(--color-text-muted);
  font-size: 0.98rem;
  margin-bottom: 1.5rem;
}

/* 知识科普文章列表卡片网格 */
.articles-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.75rem;
  margin: 3rem 0;
}
.article-card {
  background: var(--color-card-gradient);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 1.75rem;
  display: flex;
  flex-direction: column;
  transition: transform 0.25s ease, box-shadow 0.25s ease, border-color 0.25s ease;
}
.article-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg), var(--glow-primary);
  border-color: var(--color-primary-border);
}
.article-card-tag {
  font-size: 0.775rem;
  font-weight: 700;
  color: var(--color-primary);
  background-color: var(--color-primary-light);
  padding: 0.3rem 0.65rem;
  border-radius: var(--radius-sm);
  align-self: flex-start;
  margin-bottom: 1rem;
  border: 1px solid rgba(56, 189, 248, 0.2);
}
.article-card-title {
  font-size: 1.15rem;
  font-weight: 700;
  line-height: 1.45;
  color: var(--color-text-main);
  margin-bottom: 0.85rem;
}
.article-card-desc {
  font-size: 0.9rem;
  color: var(--color-text-muted);
  line-height: 1.65;
  flex-grow: 1;
  margin-bottom: 1.25rem;
}
.article-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.825rem;
  color: var(--color-text-light);
  border-top: 1px solid var(--color-border);
  padding-top: 0.85rem;
}

/* 辅助页面 (关于/条款/隐私/网站地图) 布局 */
.page-container {
  max-width: 900px;
  margin: 3.5rem auto;
  background: var(--color-surface);
  padding: 2.75rem 3.25rem;
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-md);
}
.page-container h1 {
  font-size: 2.1rem;
  font-weight: 800;
  margin-bottom: 1.25rem;
  color: var(--color-text-main);
}
.page-container h2 {
  font-size: 1.45rem;
  font-weight: 700;
  margin: 2rem 0 1rem;
  color: var(--color-text-main);
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--color-border);
}
.page-container p {
  font-size: 1rem;
  color: #cbd5e1;
  line-height: 1.8;
  margin-bottom: 1.25rem;
}
.page-container ul {
  padding-left: 1.75rem;
  margin-bottom: 1.35rem;
}
.page-container li {
  margin-bottom: 0.65rem;
  color: #cbd5e1;
  line-height: 1.7;
}

/* 网站地图分类 */
.sitemap-section {
  margin-bottom: 2.5rem;
}
.sitemap-section h2 {
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--color-text-main);
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid rgba(56, 189, 248, 0.2);
}
.sitemap-links {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.85rem;
}
.sitemap-links li a {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  color: var(--color-primary);
  font-size: 0.98rem;
}

/* ==========================================================================
   响应式断点适配 (@media)
   测试宽度标准：360px, 390px, 768px, 1024px, 1440px
   ========================================================================== */

@media (max-width: 1024px) {
  .hero-container {
    grid-template-columns: 1fr;
    gap: 3rem;
  }
  .hero-content {
    text-align: center;
  }
  .hero-cta {
    justify-content: center;
  }
  .hero-trust {
    justify-content: center;
  }
  .features-grid, .articles-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .pricing-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  :root {
    --header-height: auto;
  }
  .site-header {
    padding: 0.5rem 0;
  }
  .header-inner {
    flex-wrap: wrap;
    gap: 0.5rem;
  }
  .site-nav {
    order: 3;
    width: 100%;
    overflow-x: auto;
    white-space: nowrap;
    gap: 1rem;
    padding: 0.25rem 0;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
  }
  .site-nav::-webkit-scrollbar {
    display: none;
  }
  .nav-link {
    font-size: 0.9rem;
    padding: 0.5rem 0.25rem;
    min-height: 44px;
    display: inline-flex;
    align-items: center;
  }
  .hero-section {
    padding: 3.5rem 0 3rem;
  }
  .hero-title {
    font-size: 2.15rem;
  }
  .hero-subtitle {
    font-size: 1.1rem;
  }
  .section {
    padding: 3.5rem 0;
  }
  .section-title {
    font-size: 1.75rem;
  }
  .features-grid, .articles-grid, .media-ai-grid, .pricing-grid, .reviews-grid, .sitemap-links {
    grid-template-columns: 1fr;
  }
  .article-content, .page-container {
    padding: 1.75rem 1.25rem;
    margin: 1.5rem auto;
  }
  .footer-inner {
    flex-direction: column;
    align-items: flex-start;
  }
  .footer-nav {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.85rem;
  }
  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: 1.85rem;
  }
  .btn {
    width: 100%;
  }
  .hero-cta {
    flex-direction: column;
    width: 100%;
  }
  .hero-trust {
    flex-direction: column;
    align-items: stretch;
  }
  .hero-trust span {
    justify-content: center;
  }
  .site-header .container {
    padding-left: 1rem;
    padding-right: 1rem;
  }
  .brand-logo span {
    font-size: 1.15rem;
  }
  .node-row {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
  }
  .node-stats {
    align-items: flex-start;
    flex-direction: row;
    gap: 1rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}