/* ==========================================================================
   悠兔 YouTu - 极简高性能纯原生 CSS 样式表
   零外部依赖 | 毫秒级秒开 | 现代暗黑科技风 | 全端自适应响应式
   ========================================================================== */

:root {
  --bg-primary: #120E24;
  --bg-secondary: #16112C;
  --bg-tertiary: #1C1538;
  --bg-card: rgba(26, 20, 51, 0.72);
  --bg-card-hover: rgba(36, 28, 71, 0.88);
  
  --border-color: rgba(179, 136, 255, 0.18);
  --border-highlight: rgba(64, 220, 255, 0.35);
  --border-focus: #B388FF;

  --text-main: #F4F1FD;
  --text-muted: #B4ABD1;
  --text-dim: #8E85B2;

  --primary: #B388FF;
  --primary-hover: #9C67FF;
  --primary-glow: rgba(179, 136, 255, 0.4);
  
  --accent-cyan: #40DCFF;
  --accent-cyan-glow: rgba(64, 220, 255, 0.35);
  --accent-amber: #F59E0B;
  --accent-green: #10B981;

  --gradient-brand: linear-gradient(135deg, #B388FF 0%, #7C4DFF 50%, #40DCFF 100%);
  --gradient-card: linear-gradient(145deg, rgba(255, 255, 255, 0.04) 0%, rgba(255, 255, 255, 0.01) 100%);
  --gradient-glow: radial-gradient(circle at 50% 0%, rgba(179, 136, 255, 0.22), transparent 70%);

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

  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.5);
  --shadow-card: 0 12px 36px -10px rgba(0, 0, 0, 0.65), 0 0 1px 1px rgba(179, 136, 255, 0.15);
  --shadow-glow: 0 0 35px -5px var(--primary-glow);

  --font-sans: "Noto Sans SC", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: "Space Grotesk", Consolas, Monaco, monospace;
  --container-max: 1240px;
}

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

html {
  scroll-behavior: smooth;
  font-size: 16px;
  color-scheme: dark;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: inherit;
  text-decoration: none;
}

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

ul {
  list-style: none;
}

/* 容器与布局 */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 24px;
}

.section {
  padding: 80px 0;
  position: relative;
}

.section-title-wrap {
  text-align: center;
  max-width: 720px;
  margin: 0 auto 50px;
}

.section-tag {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 6px 14px;
  border-radius: var(--radius-full);
  background: rgba(99, 102, 241, 0.12);
  color: #818cf8;
  border: 1px solid rgba(99, 102, 241, 0.25);
  margin-bottom: 16px;
}

.section-title {
  font-size: 2.25rem;
  font-weight: 800;
  line-height: 1.25;
  letter-spacing: -0.02em;
  color: var(--text-main);
  margin-bottom: 16px;
}

.section-desc {
  font-size: 1.1rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* 渐变文字 */
.gradient-text {
  background: var(--gradient-brand);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* 按钮规范 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-weight: 600;
  font-size: 1rem;
  padding: 14px 28px;
  border-radius: var(--radius-full);
  transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  cursor: pointer;
  border: 1px solid transparent;
  min-height: 48px;
  text-align: center;
}

.btn-primary {
  background: var(--gradient-brand);
  color: #ffffff;
  box-shadow: 0 4px 20px var(--primary-glow);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(99, 102, 241, 0.55);
  filter: brightness(1.1);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-main);
  border-color: rgba(255, 255, 255, 0.15);
  backdrop-filter: blur(8px);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.3);
  transform: translateY(-2px);
}

.btn-block {
  width: 100%;
}

.btn-sm {
  padding: 10px 20px;
  font-size: 0.9rem;
  min-height: 44px;
}

/* 顶部导航 */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(10, 13, 20, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-color);
  height: 70px;
}

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

.brand-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.35rem;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: var(--text-main);
}

.brand-logo svg {
  width: 32px;
  height: 32px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
}

.nav-link {
  font-size: 0.95rem;
  color: var(--text-muted);
  font-weight: 500;
  transition: color 0.2s ease;
}

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

.nav-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

/* 主视觉区 Hero */
.hero {
  padding: 100px 0 80px;
  position: relative;
  overflow: hidden;
  text-align: center;
}

.hero-bg-glow {
  position: absolute;
  top: -100px;
  left: 50%;
  transform: translateX(-50%);
  width: 900px;
  height: 450px;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.18) 0%, rgba(6, 182, 212, 0.08) 40%, transparent 70%);
  filter: blur(60px);
  z-index: 0;
  pointer-events: none;
}

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

.hero-pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid rgba(255, 255, 255, 0.1);
  padding: 6px 16px;
  border-radius: var(--radius-full);
  font-size: 0.88rem;
  color: var(--text-muted);
  margin-bottom: 24px;
}

.hero-pill-badge {
  background: var(--gradient-brand);
  color: #fff;
  font-size: 0.72rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: var(--radius-full);
  text-transform: uppercase;
}

.hero-title {
  font-size: 3.5rem;
  font-weight: 900;
  line-height: 1.15;
  letter-spacing: -0.03em;
  margin-bottom: 20px;
  max-width: 960px;
  margin-left: auto;
  margin-right: auto;
}

.hero-desc {
  font-size: 1.2rem;
  color: var(--text-muted);
  max-width: 760px;
  margin: 0 auto 28px;
  line-height: 1.7;
}

/* 主视觉区品牌与服务深度简介卡片 */
.hero-intro-card {
  max-width: 860px;
  margin: 0 auto 36px;
  background: rgba(22, 28, 45, 0.55);
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: var(--radius-md);
  padding: 20px 26px;
  text-align: left;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
}

.hero-intro-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
  padding-bottom: 8px;
}

.hero-intro-title {
  font-size: 0.95rem;
  font-weight: 700;
  color: #818cf8;
  display: flex;
  align-items: center;
  gap: 8px;
}

.hero-intro-title svg {
  width: 18px;
  height: 18px;
}

.hero-intro-badge {
  font-size: 0.75rem;
  padding: 2px 10px;
  border-radius: var(--radius-full);
  background: rgba(16, 185, 129, 0.12);
  color: #10b981;
  border: 1px solid rgba(16, 185, 129, 0.3);
  font-weight: 600;
}

.hero-intro-text {
  font-size: 0.94rem;
  color: var(--text-muted);
  line-height: 1.65;
  margin-bottom: 14px;
}

.hero-intro-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
}

.hero-intro-point {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: var(--text-main);
  background: rgba(255, 255, 255, 0.03);
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.hero-intro-point svg {
  width: 14px;
  height: 14px;
  color: #06b6d4;
  flex-shrink: 0;
}

.hero-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  margin-bottom: 48px;
  flex-wrap: wrap;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
  max-width: 920px;
  margin: 0 auto;
  padding: 24px;
  background: var(--bg-card);
  backdrop-filter: blur(12px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card);
}

.stat-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  border-right: 1px solid var(--border-color);
}

.stat-item:last-child {
  border-right: none;
}

.stat-val {
  font-size: 1.75rem;
  font-weight: 800;
  color: var(--text-main);
  line-height: 1.2;
}

.stat-label {
  font-size: 0.82rem;
  color: var(--text-dim);
  margin-top: 4px;
}

/* 核心优势卡片 (3列) */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 36px 30px;
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
  display: flex;
  flex-direction: column;
}

.feature-card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--gradient-brand);
  opacity: 0;
  transition: opacity 0.3s ease;
}

.feature-card:hover {
  transform: translateY(-6px);
  border-color: var(--border-highlight);
  background: var(--bg-card-hover);
  box-shadow: var(--shadow-card), var(--shadow-glow);
}

.feature-card:hover::before {
  opacity: 1;
}

.feature-icon-box {
  width: 56px;
  height: 56px;
  border-radius: var(--radius-md);
  background: rgba(99, 102, 241, 0.12);
  border: 1px solid rgba(99, 102, 241, 0.25);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #818cf8;
  margin-bottom: 22px;
}

.feature-icon-box svg {
  width: 28px;
  height: 28px;
}

.feature-card h3 {
  font-size: 1.35rem;
  font-weight: 700;
  margin-bottom: 12px;
  color: var(--text-main);
}

.feature-card p {
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 20px;
  flex-grow: 1;
}

.feature-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.feature-tag-item {
  font-size: 0.78rem;
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  background: rgba(255, 255, 255, 0.04);
  color: var(--text-dim);
  border: 1px solid rgba(255, 255, 255, 0.06);
}

/* 流媒体与 AI 支持图卡 */
.support-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 32px;
}

.support-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 36px;
  transition: all 0.3s ease;
}

.support-card:hover {
  border-color: var(--border-highlight);
  background: var(--bg-card-hover);
  box-shadow: var(--shadow-card);
}

.support-header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 16px;
}

.support-badge-icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
}

.support-badge-icon.stream {
  background: rgba(239, 68, 68, 0.12);
  color: #ef4444;
  border: 1px solid rgba(239, 68, 68, 0.25);
}

.support-badge-icon.ai {
  background: rgba(6, 182, 212, 0.12);
  color: #06b6d4;
  border: 1px solid rgba(6, 182, 212, 0.25);
}

.support-header h3 {
  font-size: 1.45rem;
  font-weight: 700;
}

.support-header p {
  font-size: 0.9rem;
  color: var(--text-muted);
}

.support-card > p {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 24px;
}

.badge-chips {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
}

.chip-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 14px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid rgba(255, 255, 255, 0.07);
  border-radius: var(--radius-md);
  font-size: 0.88rem;
  font-weight: 500;
  transition: all 0.2s ease;
}

.chip-item:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.2);
}

.chip-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent-green);
  box-shadow: 0 0 8px var(--accent-green);
}

/* 价格对比表 */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
  align-items: stretch;
}

.pricing-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 40px 32px;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: all 0.3s ease;
}

.pricing-card.featured {
  border-color: #6366f1;
  background: linear-gradient(180deg, rgba(99, 102, 241, 0.08) 0%, rgba(22, 28, 45, 0.9) 100%);
  box-shadow: 0 0 35px rgba(99, 102, 241, 0.25);
  transform: scale(1.03);
  z-index: 2;
}

.pricing-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-highlight);
}

.pricing-card.featured:hover {
  transform: scale(1.03) translateY(-4px);
}

.pricing-popular-tag {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--gradient-brand);
  color: #fff;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 4px 16px;
  border-radius: var(--radius-full);
  letter-spacing: 0.05em;
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.4);
}

.plan-header {
  margin-bottom: 24px;
  text-align: center;
}

.plan-name {
  font-size: 1.35rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.plan-desc {
  font-size: 0.88rem;
  color: var(--text-dim);
}

.plan-price-wrap {
  text-align: center;
  margin-bottom: 28px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--border-color);
}

.plan-currency {
  font-size: 1.35rem;
  font-weight: 700;
  vertical-align: top;
  margin-right: 2px;
}

.plan-price {
  font-size: 3rem;
  font-weight: 900;
  line-height: 1;
}

.plan-period {
  font-size: 0.9rem;
  color: var(--text-dim);
}

.plan-features {
  margin-bottom: 32px;
  flex-grow: 1;
}

.plan-feature-item {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.92rem;
  color: var(--text-muted);
  margin-bottom: 14px;
}

.plan-feature-item svg {
  width: 18px;
  height: 18px;
  color: var(--accent-green);
  flex-shrink: 0;
}

.plan-feature-item.highlight {
  color: var(--text-main);
  font-weight: 600;
}

/* 用户评价 */
.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-lg);
  padding: 30px;
  display: flex;
  flex-direction: column;
  transition: all 0.3s ease;
}

.review-card:hover {
  transform: translateY(-4px);
  border-color: rgba(255, 255, 255, 0.15);
  background: var(--bg-card-hover);
}

.review-stars {
  color: var(--accent-amber);
  font-size: 1.1rem;
  letter-spacing: 2px;
  margin-bottom: 14px;
}

.review-quote {
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 20px;
  flex-grow: 1;
}

.review-author {
  display: flex;
  align-items: center;
  gap: 12px;
  padding-top: 16px;
  border-top: 1px solid var(--border-color);
}

.author-avatar {
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: var(--gradient-brand);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1rem;
  color: #fff;
  flex-shrink: 0;
}

.author-info h4 {
  font-size: 0.95rem;
  font-weight: 600;
}

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

/* FAQ 常见问题 (纯 CSS 手风琴) */
.faq-list {
  max-width: 840px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: all 0.25s ease;
}

.faq-item:hover {
  border-color: rgba(255, 255, 255, 0.15);
}

.faq-item[open] {
  border-color: var(--border-highlight);
  background: var(--bg-card-hover);
}

.faq-question {
  padding: 20px 24px;
  font-size: 1.05rem;
  font-weight: 600;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  list-style: none;
  user-select: none;
}

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

.faq-icon {
  width: 20px;
  height: 20px;
  transition: transform 0.25s ease;
  color: var(--text-dim);
}

.faq-item[open] .faq-icon {
  transform: rotate(180deg);
  color: var(--primary);
}

.faq-answer {
  padding: 0 24px 22px;
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.7;
  border-top: 1px solid transparent;
}

/* 底部 CTA 区域 */
.cta-banner {
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.15) 0%, rgba(6, 182, 212, 0.1) 100%);
  border: 1px solid rgba(99, 102, 241, 0.3);
  border-radius: var(--radius-lg);
  padding: 60px 40px;
  text-align: center;
  position: relative;
  overflow: hidden;
  margin-top: 40px;
}

.cta-banner h2 {
  font-size: 2.2rem;
  font-weight: 800;
  margin-bottom: 14px;
}

.cta-banner p {
  font-size: 1.1rem;
  color: var(--text-muted);
  max-width: 600px;
  margin: 0 auto 30px;
}

/* 页脚 Footer - 严格按照要求只展示4个标题，且新页面打开 */
.footer {
  background: #07090e;
  border-top: 1px solid var(--border-color);
  padding: 48px 0 36px;
  margin-top: 40px;
}

.footer-nav {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 36px;
  margin-bottom: 24px;
  flex-wrap: wrap;
}

.footer-nav a {
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-muted);
  transition: all 0.2s ease;
  padding: 6px 12px;
  border-radius: var(--radius-sm);
}

.footer-nav a:hover {
  color: var(--text-main);
  background: rgba(255, 255, 255, 0.05);
}

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

/* 子页面内容框架样式 (用于 about, terms, privacy, sitemap) */
.subpage-hero {
  padding: 60px 0 40px;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 50px;
  background: radial-gradient(circle at 50% 0%, rgba(99, 102, 241, 0.1) 0%, transparent 60%);
}

.subpage-title {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 12px;
}

.subpage-desc {
  font-size: 1.1rem;
  color: var(--text-muted);
}

.article-content {
  max-width: 860px;
  margin: 0 auto 80px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 48px 40px;
  box-shadow: var(--shadow-card);
}

.article-section {
  margin-bottom: 36px;
}

.article-section:last-child {
  margin-bottom: 0;
}

.article-section h2 {
  font-size: 1.45rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 14px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.article-section h2::before {
  content: "";
  display: inline-block;
  width: 4px;
  height: 20px;
  background: var(--primary);
  border-radius: 2px;
}

.article-section p {
  color: var(--text-muted);
  line-height: 1.8;
  margin-bottom: 12px;
  font-size: 0.98rem;
}

.article-section ul {
  padding-left: 20px;
  margin-bottom: 14px;
}

.article-section li {
  color: var(--text-muted);
  line-height: 1.8;
  list-style-type: disc;
  margin-bottom: 6px;
  font-size: 0.98rem;
}

/* 文章列表网格与卡片 (知识科普 SEO 文章索引) */
.article-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 36px;
}

.article-summary-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 26px;
  display: flex;
  flex-direction: column;
  transition: all 0.3s ease;
  position: relative;
}

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

.article-card-tag {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: var(--radius-full);
  background: rgba(99, 102, 241, 0.12);
  color: #818cf8;
  border: 1px solid rgba(99, 102, 241, 0.25);
  margin-bottom: 12px;
  align-self: flex-start;
}

.article-summary-card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  line-height: 1.4;
  margin-bottom: 10px;
  color: var(--text-main);
}

.article-summary-card h3 a:hover {
  color: #818cf8;
}

.article-summary-card p {
  font-size: 0.88rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 18px;
  flex-grow: 1;
}

.article-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-top: 1px solid var(--border-color);
  padding-top: 12px;
  font-size: 0.8rem;
  color: var(--text-dim);
}

.article-card-footer a {
  color: #06b6d4;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

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

/* 独立文章详情页专用样式 */
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: var(--text-dim);
  margin-bottom: 20px;
}

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

.breadcrumb a:hover {
  color: var(--text-main);
}

.post-header {
  margin-bottom: 30px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--border-color);
}

.post-header h1 {
  font-size: 2.1rem;
  font-weight: 800;
  line-height: 1.3;
  margin-bottom: 14px;
  color: var(--text-main);
}

.post-meta-bar {
  display: flex;
  align-items: center;
  gap: 16px;
  font-size: 0.85rem;
  color: var(--text-dim);
  flex-wrap: wrap;
}

.post-meta-item {
  display: flex;
  align-items: center;
  gap: 5px;
}

.post-body {
  color: var(--text-muted);
  font-size: 1rem;
  line-height: 1.85;
}

.post-body h2 {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--text-main);
  margin: 32px 0 14px;
  padding-bottom: 8px;
  border-bottom: 1px solid rgba(255, 255, 255, 0.06);
}

.post-body h3 {
  font-size: 1.15rem;
  font-weight: 600;
  color: #818cf8;
  margin: 20px 0 10px;
}

.post-body p {
  margin-bottom: 16px;
}

.post-body ul, .post-body ol {
  padding-left: 24px;
  margin-bottom: 18px;
}

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

.post-body blockquote {
  border-left: 3px solid var(--primary);
  background: rgba(99, 102, 241, 0.06);
  padding: 14px 18px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: 20px 0;
  color: var(--text-main);
  font-style: normal;
}

.seo-inner-link {
  color: #818cf8;
  font-weight: 600;
  text-decoration: underline;
  text-underline-offset: 3px;
  transition: color 0.2s ease;
}

.seo-inner-link:hover {
  color: #06b6d4;
}

/* 网站地图卡片列表 */
.sitemap-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.sitemap-card {
  background: rgba(255, 255, 255, 0.02);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
  transition: all 0.2s ease;
}

.sitemap-card:hover {
  background: rgba(255, 255, 255, 0.05);
  border-color: var(--border-highlight);
}

.sitemap-card h3 {
  font-size: 1.2rem;
  margin-bottom: 8px;
  color: var(--text-main);
}
.sitemap-card h3 a {
  color: var(--text-main);
  text-decoration: none;
  transition: color 0.2s ease;
}
.sitemap-card h3 a:hover {
  color: var(--accent-cyan);
}

.sitemap-card p {
  font-size: 0.9rem;
  color: var(--text-dim);
  margin-bottom: 14px;
}

.sitemap-card a {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.9rem;
  color: #818cf8;
  font-weight: 600;
}

.sitemap-card a:hover {
  text-decoration: underline;
}

/* ==========================================================================
   响应式媒体查询 (Mobile & Tablet)
   确保在手机端完美单栏显示，按钮适合手指点击 (>=44px)
   ========================================================================== */

@media (max-width: 992px) {
  .features-grid {
    grid-template-columns: 1fr;
    gap: 20px;
  }
  
  .pricing-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }
  
  .pricing-card.featured {
    transform: none;
  }
  .pricing-card.featured:hover {
    transform: translateY(-4px);
  }

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

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

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

  .hero-stats {
    grid-template-columns: repeat(2, 1fr);
    gap: 20px;
  }

  .stat-item:nth-child(2) {
    border-right: none;
  }
  
  .stat-item:nth-child(3),
  .stat-item:nth-child(4) {
    border-top: 1px solid var(--border-color);
    padding-top: 16px;
  }

  .hero-title {
    font-size: 2.6rem;
  }

  .sitemap-grid {
    grid-template-columns: 1fr;
  }

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

@media (max-width: 768px) {
  .article-grid {
    grid-template-columns: 1fr;
  }
  .section {
    padding: 56px 0;
  }

  .nav-links {
    display: none; /* 移动端精简顶部，聚焦核心行动 */
  }

  .hero {
    padding: 60px 0 50px;
  }

  .hero-title {
    font-size: 2.15rem;
  }

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

  .hero-intro-grid {
    grid-template-columns: 1fr;
    gap: 8px;
  }

  .hero-intro-card {
    padding: 16px 18px;
  }

  .hero-actions {
    flex-direction: column;
    width: 100%;
    gap: 12px;
  }

  .hero-actions .btn {
    width: 100%;
  }

  .hero-stats {
    grid-template-columns: 1fr 1fr;
    padding: 16px;
  }

  .stat-val {
    font-size: 1.45rem;
  }

  .badge-chips {
    grid-template-columns: 1fr;
  }

  .section-title {
    font-size: 1.85rem;
  }

  .cta-banner {
    padding: 40px 20px;
  }

  .cta-banner h2 {
    font-size: 1.7rem;
  }

  .cta-banner .btn {
    width: 100%;
  }

  .footer-nav {
    flex-direction: column;
    gap: 16px;
  }

  .article-content {
    padding: 28px 20px;
  }

  .subpage-title {
    font-size: 2rem;
  }
}

/* ==========================================================================
   无障碍增强 (Accessibility & Reduced Motion)
   ========================================================================== */

/* 键盘焦点环指示器 */
:focus-visible {
  outline: 2px solid var(--accent-cyan);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

/* 跳转到主要内容键盘快速入口 */
.skip-link {
  position: absolute;
  top: -120px;
  left: 20px;
  background: var(--primary);
  color: #120E24;
  padding: 12px 20px;
  font-weight: 700;
  font-size: 0.95rem;
  border-radius: var(--radius-sm);
  z-index: 999999;
  text-decoration: none;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.6);
  transition: top 0.2s cubic-bezier(0.16, 1, 0.3, 1);
}
.skip-link:focus, .skip-link:focus-visible {
  top: 20px;
  outline: 2px solid var(--accent-cyan);
  outline-offset: 2px;
}

/* 锚点防固定导航遮挡 */
section[id], div[id], article[id] {
  scroll-margin-top: 80px;
}

/* 动效减弱偏好适配 */
@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;
  }
}