/* ==========================================================================
   飞鸟 (Flying Bird) - 极简白底蓝字科技风格落地页
   纯 CSS - 无重型 JS 框架 - 群鸟壁纸 Hero + 动态图卡 - 移动端优先
   ========================================================================== */

:root {
  --bg-main: #ffffff;
  --bg-subtle: #f0f7ff;
  --bg-card: #ffffff;
  --bg-hover: #eff6ff;

  --text-title: #0f2b5c;
  --text-heading: #1e3a8a;
  --text-body: #1e40af;
  --text-secondary: #2563eb;
  --text-muted: #3b82f6;

  --border-color: #dbeafe;
  --border-active: #93c5fd;

  --primary-blue: #2563eb;
  --primary-hover: #1d4ed8;
  --accent-cyan: #0284c7;

  --shadow-sm: 0 2px 8px rgba(37, 99, 235, 0.05);
  --shadow-md: 0 10px 30px -5px rgba(37, 99, 235, 0.1);
  --shadow-lg: 0 20px 40px -10px rgba(37, 99, 235, 0.14);

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --radius-full: 9999px;

  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

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

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

body {
  background-color: var(--bg-main);
  color: var(--text-body);
  font-family: var(--font);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--primary-blue);
  text-decoration: none;
  transition: all 0.2s ease;
}

a:hover {
  color: var(--primary-hover);
}

.container {
  width: 100%;
  max-width: 1180px;
  margin: 0 auto;
  padding: 0 20px;
}

/* 按钮与 CTA 规范 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 26px;
  font-size: 0.98rem;
  font-weight: 700;
  border-radius: var(--radius-md);
  border: 2px solid transparent;
  cursor: pointer;
  transition: all 0.25s ease;
  text-decoration: none;
}

.btn-primary {
  background-color: var(--primary-blue);
  color: #ffffff !important;
  box-shadow: 0 4px 14px rgba(37, 99, 235, 0.25);
}

.btn-primary:hover {
  background-color: var(--primary-hover);
  box-shadow: 0 6px 18px rgba(37, 99, 235, 0.35);
  transform: translateY(-2px);
}

.btn-outline {
  background-color: #ffffff;
  color: var(--primary-blue) !important;
  border-color: var(--primary-blue);
}

.btn-outline:hover {
  background-color: var(--bg-subtle);
  transform: translateY(-2px);
}

.btn-sm {
  padding: 8px 18px;
  font-size: 0.88rem;
  border-radius: var(--radius-sm);
}

/* 徽章 */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  background-color: rgba(255, 255, 255, 0.92);
  border: 1px solid var(--border-color);
  color: var(--text-heading);
  font-size: 0.85rem;
  font-weight: 600;
  border-radius: var(--radius-full);
}

.badge-dot {
  width: 8px;
  height: 8px;
  background-color: var(--primary-blue);
  border-radius: 50%;
  animation: pulse-ring 2s infinite;
}

@keyframes pulse-ring {
  0% { transform: scale(0.95); opacity: 0.8; }
  50% { transform: scale(1.15); opacity: 1; }
  100% { transform: scale(0.95); opacity: 0.8; }
}

/* 页眉 Header 与导航目录 */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  padding: 14px 0;
}

.nav-wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-title);
}

.logo span {
  color: var(--primary-blue);
}

.nav-dir {
  display: flex;
  align-items: center;
  gap: 24px;
  list-style: none;
}

.nav-dir a {
  color: var(--text-heading);
  font-weight: 600;
  font-size: 0.92rem;
  padding: 4px 0;
  position: relative;
}

.nav-dir a:hover {
  color: var(--primary-blue);
}

.nav-dir a::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0%;
  height: 2px;
  background-color: var(--primary-blue);
  transition: all 0.2s ease;
}

.nav-dir a:hover::after {
  width: 100%;
}

/* 模块标题 */
.section-head {
  text-align: center;
  max-width: 680px;
  margin: 0 auto 44px;
}

.section-tag {
  color: var(--primary-blue);
  font-weight: 700;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 6px;
  display: block;
}

.section-title {
  color: var(--text-title);
  font-size: 2rem;
  font-weight: 800;
  margin-bottom: 10px;
}

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

/* 主视觉区 Hero (群鸟蓝天高清壁纸 Hero) */
.hero {
  padding: 76px 0 64px;
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.85) 0%, rgba(240, 247, 255, 0.88) 100%), url('../images/bird_wallpaper.jpg') center/cover no-repeat;
  position: relative;
  overflow: hidden;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 44px;
  align-items: center;
}

.hero-left {
  text-align: left;
}

.hero-left h1 {
  font-size: 2.85rem;
  color: var(--text-title);
  line-height: 1.22;
  margin: 18px 0;
  letter-spacing: -0.5px;
}

.hero-left h1 span {
  color: var(--primary-blue);
}

.hero-subtitle {
  font-size: 1.12rem;
  color: var(--text-body);
  margin-bottom: 30px;
  line-height: 1.6;
  max-width: 580px;
}

.hero-cta {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 36px;
  flex-wrap: wrap;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 14px;
  padding-top: 24px;
  border-top: 1px solid var(--border-color);
}

.stat-item {
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(8px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 12px;
  text-align: center;
}

.stat-num {
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--primary-blue);
}

.stat-desc {
  font-size: 0.8rem;
  color: var(--text-secondary);
  font-weight: 600;
}

/* Hero 右侧动态科技图卡 */
.hero-visual-card {
  background: rgba(255, 255, 255, 0.96);
  backdrop-filter: blur(12px);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow-lg);
  animation: float-card 4s ease-in-out infinite;
  position: relative;
}

@keyframes float-card {
  0%, 100% { transform: translateY(0px); }
  50% { transform: translateY(-8px); }
}

.card-top-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 18px;
}

.card-top-title {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--text-title);
}

.card-top-badge {
  background-color: var(--bg-subtle);
  color: var(--primary-blue);
  border: 1px solid var(--border-active);
  font-size: 0.75rem;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: var(--radius-full);
}

/* 动态下行波形仪表 */
.dynamic-meter {
  background: var(--bg-subtle);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 16px;
  margin-bottom: 18px;
  text-align: center;
}

.meter-num {
  font-size: 2.1rem;
  font-weight: 800;
  color: var(--primary-blue);
  line-height: 1.1;
}

.meter-label {
  font-size: 0.8rem;
  color: var(--text-secondary);
  font-weight: 600;
  margin-top: 4px;
}

.wave-bar-wrap {
  height: 6px;
  background-color: #dbeafe;
  border-radius: var(--radius-full);
  margin-top: 10px;
  overflow: hidden;
}

.wave-bar-fill {
  height: 100%;
  width: 92%;
  background: linear-gradient(90deg, #60a5fa, #2563eb, #1d4ed8);
  background-size: 200% 100%;
  border-radius: var(--radius-full);
  animation: wave-anim 2.5s linear infinite;
}

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

/* 实时动态节点状态列表 */
.dynamic-nodes {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.node-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 12px;
  background-color: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 0.84rem;
}

.node-label {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
  color: var(--text-heading);
}

.node-ping {
  color: var(--accent-cyan);
  font-weight: 700;
  font-family: monospace;
}

/* 核心优势卡片（3个） */
.features-section {
  padding: 70px 0;
  background-color: #ffffff;
}

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

.card-item {
  background-color: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 28px 22px;
  transition: all 0.25s ease;
}

.card-item:hover {
  border-color: var(--border-active);
  box-shadow: var(--shadow-md);
  transform: translateY(-4px);
  background-color: var(--bg-hover);
}

.card-icon {
  width: 52px;
  height: 52px;
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary-blue);
  margin-bottom: 18px;
}

.card-item h3 {
  font-size: 1.25rem;
  color: var(--text-title);
  margin-bottom: 10px;
}

.card-item p {
  font-size: 0.92rem;
  color: var(--text-body);
  line-height: 1.6;
}

/* 流媒体与 AI 支持图卡 */
.unlock-section {
  padding: 70px 0;
  background-color: var(--bg-subtle);
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
}

.unlock-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.unlock-card {
  background: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 28px;
}

.unlock-card-head {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 16px;
}

.unlock-card-head h3 {
  font-size: 1.25rem;
  color: var(--text-title);
}

.tags-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 16px;
}

.tag {
  background-color: var(--bg-subtle);
  border: 1px solid var(--border-color);
  color: var(--text-heading);
  font-size: 0.85rem;
  font-weight: 700;
  padding: 6px 14px;
  border-radius: var(--radius-sm);
}

/* 真实高性价比套餐价格对比表 */
.pricing-section {
  padding: 80px 0;
  background-color: #ffffff;
}

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  align-items: stretch;
}

.price-card {
  background: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 32px 24px;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: all 0.25s ease;
}

.price-card.popular {
  border: 2px solid var(--primary-blue);
  box-shadow: var(--shadow-md);
}

.price-badge {
  position: absolute;
  top: -13px;
  right: 20px;
  background-color: var(--primary-blue);
  color: #ffffff;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 3px 10px;
  border-radius: var(--radius-full);
}

.price-card h3 {
  font-size: 1.3rem;
  color: var(--text-title);
  margin-bottom: 6px;
}

.price-desc {
  font-size: 0.88rem;
  color: var(--text-secondary);
  margin-bottom: 20px;
}

.price-num {
  font-size: 2.25rem;
  font-weight: 800;
  color: var(--text-title);
  margin-bottom: 20px;
}

.price-num span {
  font-size: 0.9rem;
  color: var(--text-secondary);
  font-weight: 500;
}

.price-list {
  margin-bottom: 28px;
  flex-grow: 1;
}

.price-list li {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
  color: var(--text-body);
  margin-bottom: 10px;
}

.price-list svg {
  color: var(--primary-blue);
  flex-shrink: 0;
}

/* 9篇 SEO 文章图卡展区 (位于价格板块下方) */
.articles-section {
  padding: 80px 0;
  background-color: var(--bg-subtle);
  border-top: 1px solid var(--border-color);
  border-bottom: 1px solid var(--border-color);
}

.articles-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.art-card {
  background: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px;
  display: flex;
  flex-direction: column;
  transition: all 0.25s ease;
}

.art-card:hover {
  border-color: var(--border-active);
  box-shadow: var(--shadow-md);
  transform: translateY(-4px);
}

.art-card-badge {
  color: var(--primary-blue);
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 8px;
}

.art-card h3 {
  font-size: 1.1rem;
  color: var(--text-title);
  line-height: 1.45;
  margin-bottom: 10px;
}

.art-card h3 a {
  color: var(--text-title);
}

.art-card h3 a:hover {
  color: var(--primary-blue);
}

.art-snippet {
  font-size: 0.88rem;
  color: var(--text-body);
  line-height: 1.55;
  margin-bottom: 18px;
  flex-grow: 1;
}

.art-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.78rem;
  color: var(--text-secondary);
  padding-top: 12px;
  border-top: 1px solid var(--border-color);
}

/* 用户评价 */
.reviews-section {
  padding: 70px 0;
  background-color: #ffffff;
}

.reviews-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.review-card {
  background: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 22px;
  box-shadow: var(--shadow-sm);
}

.review-stars {
  color: #0284c7;
  font-size: 0.9rem;
  margin-bottom: 10px;
}

.review-text {
  font-size: 0.9rem;
  color: var(--text-body);
  line-height: 1.5;
  margin-bottom: 14px;
}

.review-author {
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--text-title);
}

/* 常见问题解答 (FAQ) */
.faq-section {
  padding: 70px 0;
  background-color: var(--bg-subtle);
  border-top: 1px solid var(--border-color);
}

.faq-list {
  max-width: 760px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.faq-box {
  background: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 18px 22px;
}

.faq-box h4 {
  font-size: 1.02rem;
  color: var(--text-title);
  margin-bottom: 8px;
}

.faq-box p {
  font-size: 0.9rem;
  color: var(--text-body);
  line-height: 1.55;
  margin-bottom: 0;
}

/* 页脚：严格规范要求只保留四个标题，新页面打开 */
.footer {
  background-color: #ffffff;
  border-top: 1px solid var(--border-color);
  padding: 36px 0 24px;
  text-align: center;
}

.footer-nav {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 32px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.footer-nav a {
  color: var(--text-heading);
  font-size: 1rem;
  font-weight: 700;
}

.footer-nav a:hover {
  color: var(--primary-blue);
}

.footer-copyright {
  font-size: 0.85rem;
  color: var(--text-secondary);
}

/* 移动端响应式 (Mobile-First 兼容) */
@media (max-width: 868px) {
  .nav-dir { display: none; }
  .hero-grid { grid-template-columns: 1fr; gap: 32px; }
  .hero-left { text-align: center; }
  .hero-left h1 { font-size: 2.1rem; }
  .hero-subtitle { margin: 0 auto 24px; }
  .hero-cta { justify-content: center; }
  .features-grid, .pricing-grid, .reviews-grid, .unlock-grid, .articles-grid { grid-template-columns: 1fr; }
  .hero-stats { grid-template-columns: 1fr; }
  .footer-nav { gap: 18px; flex-direction: column; }
}