:root {
  /* 晴空航站风 Theme Variables */
  --primary: #1E80FF;           /* 晴空蓝 */
  --primary-hover: #1565C0;
  --bg-color-start: #DFF0FF;    /* 浅蓝晴空渐变起 */
  --bg-color-end: #F7FBFF;      /* 浅蓝晴空渐变止 */
  --bg-color: transparent;      /* 覆盖部分组件行内设定的原背景 */
  --card-bg: rgba(255, 255, 255, 0.8); /* 卡片白 80% 半透明 */
  --text-main: #0B3556;         /* 文字深蓝 */
  --text-muted: #2A4F6D;        
  --border-color: #7DD3FC;      /* 浅天蓝描边 */
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  background: linear-gradient(180deg, var(--bg-color-start) 0%, var(--bg-color-end) 100%);
  background-attachment: fixed; /* 保证渐变撑满全屏 */
  color: var(--text-main);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden; /* 防止云层飞出屏幕时产生水平滚动条 */
}

a { text-decoration: none; color: inherit; }
.container { max-width: 1200px; margin: 0 auto; padding: 0 20px; position: relative; z-index: 10; }

/* Header */
header {
  background: var(--card-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 1px 3px rgba(30, 128, 255, 0.1);
  position: sticky;
  top: 0;
  z-index: 100;
  border-bottom: 1px solid var(--border-color);
}

.header-inner { display: flex; justify-content: space-between; align-items: center; height: 70px; }
.logo { font-size: 1.5rem; font-weight: bold; color: var(--primary); }
.main-nav { display: flex; gap: 24px; align-items: center; }
.main-nav a { color: var(--text-main); font-weight: 500; transition: color 0.2s ease; }
.main-nav a:hover { color: var(--primary); }

/* Buttons */
.btn {
  display: inline-flex; align-items: center; justify-content: center;
  background-color: var(--primary); color: white;
  padding: 12px 28px; border-radius: 8px; font-weight: 600;
  transition: opacity 0.2s ease, transform 0.2s ease;
  min-height: 44px; border: none; cursor: pointer;
}
.btn:hover { opacity: 0.9; }
.btn-outline { background-color: transparent; color: var(--primary); border: 1px solid var(--primary); }
.btn-outline:hover { background-color: var(--primary); color: white; border-color: var(--primary); }

/* Section Common */
section { padding: 100px 0; position: relative; z-index: 10; }
section.container { padding: 100px 20px; } /* 修复 padding 被 .container 覆盖导致间距过窄的问题 */
.section-title { text-align: center; font-size: 2.2rem; margin-bottom: 60px; color: var(--text-main); }

/* Hero Section */
.hero { text-align: center; background: transparent; padding: 100px 0; }
.hero h1 { font-size: 3.5rem; line-height: 1.2; margin-bottom: 24px; }
.hero p { font-size: 1.25rem; color: var(--text-muted); max-width: 750px; margin: 0 auto 40px; }

/* Grid Layouts */
.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 30px; }
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 30px; }

/* Cards - Unified styling for Clear Sky Terminal */
.card, .pricing-card, details, .page-content {
  background: var(--card-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--border-color);
  border-radius: 18px;
  box-shadow: 0 8px 32px rgba(30, 128, 255, 0.1);
}

.card { padding: 40px 30px; text-align: center; }
.card h3 { font-size: 1.25rem; margin: 20px 0 15px; }
.card p { color: var(--text-muted); }
.icon { font-size: 3rem; margin-bottom: 10px; }

/* Pricing */
.pricing-card { padding: 40px; display: flex; flex-direction: column; }
.pricing-card.popular { border: 2px solid var(--primary); transform: translateY(-10px); position: relative; }
.popular-badge {
  position: absolute; top: -12px; left: 50%; transform: translateX(-50%);
  background: var(--primary); color: white; padding: 4px 12px; border-radius: 20px;
  font-size: 0.875rem; font-weight: bold;
}
.price { font-size: 3rem; font-weight: bold; color: var(--text-main); margin: 20px 0; }
.price span { font-size: 1rem; color: var(--text-muted); font-weight: normal; }
.features-list { list-style: none; margin: 30px 0; flex-grow: 1; }
.features-list li { margin-bottom: 15px; color: var(--text-muted); position: relative; padding-left: 28px; text-align: left; }
.features-list li::before { content: "✓"; position: absolute; left: 0; color: var(--primary); font-weight: bold; }

/* Reviews */
.review-card { text-align: left; }
.review-text { font-style: italic; margin-bottom: 20px; }
.review-author { font-weight: bold; color: var(--primary); }

/* FAQ */
.faq-list { max-width: 800px; margin: 0 auto; }
details { margin-bottom: 16px; overflow: hidden; }
summary { padding: 20px; font-weight: 600; cursor: pointer; list-style: none; position: relative; }
summary::-webkit-details-marker { display: none; }
summary::after { content: "+"; position: absolute; right: 20px; top: 50%; transform: translateY(-50%); font-size: 1.5rem; color: var(--primary); }
details[open] summary::after { content: "-"; }
details p { padding: 0 20px 20px; color: var(--text-muted); }

/* Footer */
footer { background: transparent; padding: 60px 0 40px; border-top: 1px solid var(--border-color); text-align: center; position: relative; z-index: 10; }
.footer-nav { display: flex; justify-content: center; gap: 30px; margin-bottom: 40px; flex-wrap: wrap; }
.footer-nav a { color: var(--text-muted); font-weight: 500; }
.footer-nav a:hover { color: var(--primary); }
.copyright { color: var(--text-muted); font-size: 0.875rem; }

/* Static Pages */
.page-header { text-align: center; padding: 60px 0; background: transparent; border-bottom: 1px solid var(--border-color); }
.page-content { max-width: 800px; margin: 60px auto; padding: 40px; }
.page-content h2 { margin: 30px 0 15px; color: var(--primary); }
.page-content p, .page-content ul { margin-bottom: 15px; color: var(--text-muted); }
.page-content ul { padding-left: 20px; }

/* ==============================================================
   Sky Decorations (Animations & Visuals)
   ============================================================== */
.sky-decorations {
  position: fixed; top: 0; left: 0; width: 100%; height: 100%;
  pointer-events: none; z-index: 1; /* 垫底图层，不影响任何组件点击 */
  overflow: hidden;
}

/* 暖金日光 */
.sunlight {
  position: absolute; top: -20vh; right: -20vh;
  width: 70vh; height: 70vh;
  background: radial-gradient(circle, rgba(255, 223, 112, 0.25) 0%, rgba(255, 223, 112, 0) 65%);
  border-radius: 50%;
  animation: sun-breathe 9s ease-in-out infinite;
}

/* 视差云层 */
.cloud {
  position: absolute;
  background: rgba(255, 255, 255, 0.7);
  border-radius: 150px;
  filter: blur(25px);
}
.cloud-1 {
  top: 12%; left: -400px; width: 350px; height: 120px;
  animation: cloud-traverse 60s linear infinite;
}
.cloud-2 {
  top: 45%; left: -500px; width: 450px; height: 160px;
  animation: cloud-traverse 95s linear infinite 9s; /* 延迟 9s */
}
.cloud-3 {
  top: 65%; right: 10%; width: 300px; height: 100px;
  animation: cloud-float 34s ease-in-out infinite;
}

/* 航线穿行 */
.flight-route {
  position: absolute; top: 24%; left: 0; width: 100%; height: 0;
  border-top: 2px dashed rgba(125, 211, 252, 0.6);
  /* 两端渐隐 */
  mask-image: linear-gradient(90deg, transparent 0%, black 15%, black 85%, transparent 100%);
  -webkit-mask-image: linear-gradient(90deg, transparent 0%, black 15%, black 85%, transparent 100%);
}
.flight-dot {
  position: absolute; top: -5px; left: 0;
  width: 8px; height: 8px; border-radius: 50%;
  background: var(--primary);
  box-shadow: 0 0 12px 4px rgba(30, 128, 255, 0.5);
  animation: flight-traverse 9s linear infinite;
}

/* 动效关键帧 (仅使用 transform 与 opacity) */
@keyframes sun-breathe {
  0%, 100% { transform: scale(1); opacity: 0.6; }
  50% { transform: scale(1.15); opacity: 1; }
}
@keyframes cloud-traverse {
  0% { transform: translateX(0); }
  100% { transform: translateX(calc(100vw + 800px)); }
}
@keyframes cloud-float {
  0%, 100% { transform: translateX(0) translateY(0); }
  50% { transform: translateX(-60px) translateY(25px); }
}
@keyframes flight-traverse {
  0% { transform: translateX(-50px); opacity: 0; }
  15% { opacity: 1; }
  85% { opacity: 1; }
  100% { transform: translateX(100vw); opacity: 0; }
}

/* 降级处理：尊重用户减弱动画偏好 */
@media (prefers-reduced-motion: reduce) {
  .sunlight, .cloud-1, .cloud-2, .cloud-3, .flight-dot {
    animation: none !important;
  }
  .flight-dot { display: none; }
}

/* Media Queries for Mobile Responsiveness */
@media (max-width: 768px) {
  .hero h1 { font-size: 2.2rem; }
  .hero p { font-size: 1.05rem; }
  .grid-3, .grid-2 { grid-template-columns: 1fr; }
  .pricing-card.popular { transform: none; }
  .header-inner { flex-direction: column; height: auto; padding: 15px 0; gap: 15px; }
  .main-nav { flex-wrap: wrap; justify-content: center; gap: 12px; }
  .header-inner .btn { padding: 12px 16px; font-size: 1rem; width: 100%; }
  .btn { width: 100%; }
  section { padding: 60px 0; }
  section.container { padding: 60px 20px; }
}

/* A11y: Skip Link and Focus */
.skip-link {
    position: absolute;
    top: -50px;
    left: 10px;
    background: var(--primary);
    color: white;
    padding: 10px 15px;
    z-index: 9999;
    border-radius: 4px;
    font-weight: bold;
    text-decoration: none;
    transition: top 0.2s;
}
.skip-link:focus {
    top: 10px;
}
*:focus-visible {
    outline: 3px solid var(--primary);
    outline-offset: 2px;
}
/* Scroll margin for fixed header */
section[id], h2[id], h3[id], div[id], main[id] {
    scroll-margin-top: 90px;
}