/* ============================================
   快连极速 Official Website - v1.0
   Clean, modern, light theme
   ============================================ */

@import url('https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@300;400;500;600;700&family=Noto+Sans+JP:wght@300;400;500;700&family=Poppins:wght@300;400;500;600;700&display=swap');

:root {
  --primary: #2563EB;
  --primary-light: #DBEAFE;
  --primary-dark: #1D4ED8;
  --accent: #0EA5E9;
  --text: #1E293B;
  --text-secondary: #64748B;
  --text-light: #94A3B8;
  --bg: #FFFFFF;
  --bg-soft: #F8FAFC;
  --bg-card: #FFFFFF;
  --border: #E2E8F0;
  --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.08);
  --shadow-lg: 0 10px 40px rgba(0,0,0,0.1);
  --radius: 12px;
  --radius-lg: 20px;
  --max-w: 1200px;
  --header-h: 72px;
  --font: 'Poppins', 'Noto Sans SC', 'Noto Sans JP', system-ui, sans-serif;
}

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

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

body {
  font-family: var(--font);
  color: var(--text);
  background: var(--bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a { text-decoration: none; color: inherit; transition: all .25s; }
img { max-width: 100%; display: block; }
ul { list-style: none; }

.container { max-width: var(--max-w); margin: 0 auto; padding: 0 24px; }

/* ── Header ───────────────────────────────── */
.site-header {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  height: var(--header-h);
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  transition: box-shadow .3s;
}
.site-header.scrolled { box-shadow: var(--shadow-md); }

.header-inner {
  max-width: var(--max-w); margin: 0 auto; padding: 0 24px;
  height: 100%; display: flex; align-items: center; justify-content: space-between;
}

.logo { display: flex; align-items: center; gap: 10px; font-weight: 700; font-size: 20px; color: var(--primary); }
.logo img { height: 36px; width: 36px; border-radius: 8px; }

.main-nav { display: flex; gap: 32px; }
.main-nav a {
  font-size: 15px; font-weight: 500; color: var(--text-secondary);
  padding: 6px 0; position: relative;
}
.main-nav a::after {
  content: ''; position: absolute; bottom: -2px; left: 0; width: 0; height: 2px;
  background: var(--primary); border-radius: 1px; transition: width .3s;
}
.main-nav a:hover, .main-nav a.active { color: var(--primary); }
.main-nav a:hover::after, .main-nav a.active::after { width: 100%; }

.header-right { display: flex; align-items: center; gap: 16px; }

/* Language Switcher */
.lang-switcher { position: relative; }
.lang-btn {
  display: flex; align-items: center; gap: 6px;
  padding: 6px 12px; border-radius: 8px; font-size: 14px; font-weight: 500;
  color: var(--text-secondary); cursor: pointer; border: 1px solid var(--border);
  background: var(--bg); transition: all .2s;
}
.lang-btn:hover { border-color: var(--primary); color: var(--primary); }
.lang-btn svg { width: 16px; height: 16px; }

.lang-dropdown {
  position: absolute; top: calc(100% + 8px); right: 0;
  background: var(--bg); border: 1px solid var(--border); border-radius: var(--radius);
  box-shadow: var(--shadow-lg); min-width: 160px;
  opacity: 0; visibility: hidden; transform: translateY(-8px);
  transition: all .25s;
}
.lang-dropdown.show { opacity: 1; visibility: visible; transform: translateY(0); }
.lang-dropdown a {
  display: block; padding: 10px 16px; font-size: 14px;
  color: var(--text-secondary); transition: all .15s;
}
.lang-dropdown a:hover { background: var(--bg-soft); color: var(--primary); }

/* Mobile hamburger */
.mobile-toggle {
  display: none; flex-direction: column; gap: 5px; cursor: pointer;
  background: none; border: none; padding: 4px;
}
.mobile-toggle span {
  width: 22px; height: 2px; background: var(--text); border-radius: 1px;
  transition: all .3s;
}

/* ── Hero ─────────────────────────────────── */
.hero {
  padding: calc(var(--header-h) + 80px) 0 80px;
  background: linear-gradient(135deg, #F0F7FF 0%, #E8F4FD 40%, #FFF 100%);
  position: relative; overflow: hidden;
}
.hero::before {
  content: ''; position: absolute; top: -200px; right: -200px;
  width: 600px; height: 600px; border-radius: 50%;
  background: radial-gradient(circle, rgba(37,99,235,0.06) 0%, transparent 70%);
}
.hero-inner {
  max-width: var(--max-w); margin: 0 auto; padding: 0 24px;
  display: flex; align-items: center; gap: 60px;
}
.hero-text { flex: 1; }
.hero-text h1 {
  font-size: clamp(32px, 4vw, 52px); font-weight: 700; line-height: 1.2;
  margin-bottom: 20px; color: var(--text);
}
.hero-text h1 span { color: var(--primary); }
.hero-text p {
  font-size: 18px; color: var(--text-secondary); margin-bottom: 32px;
  max-width: 480px; line-height: 1.8;
}
.hero-image { flex: 1; display: flex; justify-content: center; }
.hero-image .img-placeholder {
  width: 100%; max-width: 520px; aspect-ratio: 4/3;
  background: linear-gradient(135deg, var(--primary-light) 0%, #E0ECFF 100%);
  border-radius: var(--radius-lg); display: flex; align-items: center; justify-content: center;
  color: var(--primary); font-size: 14px; font-weight: 500;
}

.btn {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 14px 32px; border-radius: 10px; font-size: 16px; font-weight: 600;
  transition: all .3s; cursor: pointer; border: none;
}
.btn-primary {
  background: var(--primary); color: #fff;
  box-shadow: 0 4px 14px rgba(37,99,235,0.3);
}
.btn-primary:hover {
  background: var(--primary-dark); transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(37,99,235,0.4);
}
.btn-outline {
  background: transparent; color: var(--primary);
  border: 2px solid var(--primary);
}
.btn-outline:hover { background: var(--primary); color: #fff; }

/* ── Sections ─────────────────────────────── */
.section { padding: 100px 0; }
.section-alt { background: var(--bg-soft); }

.section-header {
  text-align: center; margin-bottom: 60px;
}
.section-header h2 {
  font-size: clamp(28px, 3vw, 40px); font-weight: 700; margin-bottom: 16px;
}
.section-header p {
  font-size: 17px; color: var(--text-secondary); max-width: 600px; margin: 0 auto;
}

/* ── What is VPN ──────────────────────────── */
.vpn-intro {
  display: flex; align-items: center; gap: 60px;
}
.vpn-intro-text { flex: 1; }
.vpn-intro-text h3 {
  font-size: 18px; color: var(--primary); font-weight: 600; margin-bottom: 12px;
}
.vpn-intro-text p { font-size: 16px; color: var(--text-secondary); line-height: 1.8; }
.vpn-intro-image { flex: 1; }
.vpn-intro-image .img-placeholder {
  width: 100%; aspect-ratio: 16/10;
  background: linear-gradient(135deg, #F0F7FF, #E8F0FE);
  border-radius: var(--radius-lg); display: flex; align-items: center; justify-content: center;
  color: var(--text-light); font-size: 14px;
}

/* ── Why Use ──────────────────────────────── */
.why-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px;
  margin-bottom: 40px;
}
.why-tag {
  display: flex; align-items: center; gap: 12px;
  padding: 16px 20px; background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius); transition: all .3s;
}
.why-tag:hover { border-color: var(--primary); box-shadow: var(--shadow); }
.why-tag-icon {
  width: 44px; height: 44px; border-radius: 10px;
  background: var(--primary-light); display: flex; align-items: center; justify-content: center;
  flex-shrink: 0;
}
.why-tag-icon svg { width: 22px; height: 22px; color: var(--primary); }
.why-tag span { font-weight: 600; font-size: 15px; }
.why-desc { font-size: 15px; color: var(--text-secondary); line-height: 1.9; max-width: 900px; margin: 0 auto; text-align: center; }

/* ── Features ─────────────────────────────── */
.features-grid {
  display: grid; grid-template-columns: repeat(2, 1fr); gap: 24px;
}
.feature-card {
  padding: 36px; background: var(--bg-card); border: 1px solid var(--border);
  border-radius: var(--radius-lg); transition: all .3s; position: relative; overflow: hidden;
}
.feature-card::before {
  content: ''; position: absolute; top: 0; left: 0; right: 0; height: 3px;
  background: linear-gradient(90deg, var(--primary), var(--accent));
  transform: scaleX(0); transform-origin: left; transition: transform .3s;
}
.feature-card:hover { box-shadow: var(--shadow-md); transform: translateY(-4px); }
.feature-card:hover::before { transform: scaleX(1); }
.feature-card .icon-wrap {
  width: 52px; height: 52px; border-radius: 12px;
  background: var(--primary-light); display: flex; align-items: center; justify-content: center;
  margin-bottom: 20px;
}
.feature-card .icon-wrap svg { width: 26px; height: 26px; color: var(--primary); }
.feature-card h3 { font-size: 20px; font-weight: 600; margin-bottom: 10px; }
.feature-card p { font-size: 15px; color: var(--text-secondary); line-height: 1.7; }

/* ── Use Cases ────────────────────────────── */
.use-case-tabs { display: flex; gap: 12px; justify-content: center; margin-bottom: 40px; flex-wrap: wrap; }
.use-case-tab {
  padding: 10px 24px; border-radius: 40px; font-size: 15px; font-weight: 500;
  cursor: pointer; border: 1px solid var(--border); color: var(--text-secondary);
  background: var(--bg); transition: all .25s;
}
.use-case-tab.active, .use-case-tab:hover {
  background: var(--primary); color: #fff; border-color: var(--primary);
}

.use-case-panel { display: none; }
.use-case-panel.active { display: flex; }
.use-case-panel {
  align-items: center; gap: 48px;
  max-width: 960px; margin: 0 auto;
}
.use-case-image { flex: 0 0 380px; }
.use-case-image .img-placeholder {
  width: 100%; aspect-ratio: 4/3;
  background: linear-gradient(135deg, #EEF4FF, #DBEAFE);
  border-radius: var(--radius-lg); display: flex; align-items: center; justify-content: center;
  color: var(--text-light); font-size: 14px;
}
.use-case-text { flex: 1; }
.use-case-text p { font-size: 15px; color: var(--text-secondary); line-height: 1.9; }

/* ── Brand Vision ─────────────────────────── */
.vision-section {
  text-align: center; padding: 100px 0;
  background: linear-gradient(135deg, #1E293B 0%, #0F172A 100%);
  color: #fff;
}
.vision-section h2 { color: #fff; margin-bottom: 20px; }
.vision-section p { color: #CBD5E1; max-width: 640px; margin: 0 auto 40px; font-size: 16px; line-height: 1.9; }
.vision-section .img-placeholder {
  width: 200px; height: 200px; margin: 0 auto; border-radius: 50%;
  background: radial-gradient(circle, rgba(37,99,235,0.3) 0%, transparent 70%);
  display: flex; align-items: center; justify-content: center;
  color: #64748B; font-size: 13px;
}

/* ── Footer ───────────────────────────────── */
.site-footer {
  background: #F8FAFC; border-top: 1px solid var(--border); padding: 60px 0 30px;
}
.footer-grid {
  max-width: var(--max-w); margin: 0 auto; padding: 0 24px;
  display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: 40px;
}
.footer-brand .logo { margin-bottom: 16px; }
.footer-brand p { font-size: 14px; color: var(--text-secondary); line-height: 1.7; }
.footer-col h4 { font-size: 14px; font-weight: 600; margin-bottom: 16px; text-transform: uppercase; letter-spacing: 0.5px; }
.footer-col a { display: block; font-size: 14px; color: var(--text-secondary); padding: 4px 0; }
.footer-col a:hover { color: var(--primary); }
.footer-bottom {
  max-width: var(--max-w); margin: 0 auto; padding: 24px 24px 0;
  border-top: 1px solid var(--border); margin-top: 40px;
  display: flex; justify-content: space-between; align-items: center;
  font-size: 13px; color: var(--text-light);
}

/* ── Download Page ────────────────────────── */
.download-hero {
  padding: calc(var(--header-h) + 60px) 0 40px;
  background: var(--bg-soft); text-align: center;
}
.download-hero h1 { font-size: 36px; font-weight: 700; margin-bottom: 12px; }
.download-hero p { font-size: 16px; color: var(--text-secondary); }

.platform-tabs {
  display: flex; justify-content: center; gap: 12px; margin: 40px 0;
  flex-wrap: wrap;
}
.platform-tab {
  display: flex; align-items: center; gap: 8px;
  padding: 12px 28px; border-radius: 40px; font-size: 15px; font-weight: 600;
  cursor: pointer; background: var(--bg); border: 1px solid var(--border);
  color: var(--text); transition: all .25s;
}
.platform-tab svg { width: 20px; height: 20px; }
.platform-tab.active { background: var(--text); color: #fff; border-color: var(--text); }

.download-panel { display: none; }
.download-panel.active { display: flex; }
.download-panel {
  max-width: 900px; margin: 0 auto; padding: 0 24px;
  align-items: center; gap: 60px;
}
.download-device { flex: 0 0 340px; }
.download-device .img-placeholder {
  width: 100%; aspect-ratio: 1/1;
  background: linear-gradient(135deg, #F1F5F9, #E2E8F0);
  border-radius: var(--radius-lg); display: flex; align-items: center; justify-content: center;
  color: var(--text-light); font-size: 13px;
}
.download-info { flex: 1; }
.download-info h2 { font-size: 24px; font-weight: 700; margin-bottom: 16px; }
.download-info .meta { margin-bottom: 20px; }
.download-info .meta p { font-size: 14px; color: var(--text-secondary); margin-bottom: 4px; }
.download-info .tips {
  background: rgba(37,99,235,0.05); border-radius: var(--radius);
  padding: 16px 20px; margin-top: 20px;
}
.download-info .tips h4 { font-size: 14px; color: var(--primary); margin-bottom: 10px; }
.download-info .tips li { font-size: 13px; color: var(--text-secondary); padding: 3px 0; }
.download-info .tips li::before { content: '• '; color: var(--primary); }

/* ── FAQ Page ─────────────────────────────── */
.faq-hero {
  padding: calc(var(--header-h) + 60px) 0 40px;
  background: var(--bg-soft); text-align: center;
}
.faq-hero h1 { font-size: 36px; font-weight: 700; }

.faq-list { max-width: 800px; margin: 60px auto; padding: 0 24px; }
.faq-item {
  border-bottom: 1px solid var(--border); padding: 20px 0;
}
.faq-q {
  display: flex; justify-content: space-between; align-items: center;
  cursor: pointer; font-size: 16px; font-weight: 600; color: var(--text);
  gap: 16px;
}
.faq-q svg { width: 20px; height: 20px; flex-shrink: 0; color: var(--text-light); transition: transform .3s; }
.faq-item.open .faq-q svg { transform: rotate(180deg); }
.faq-a {
  max-height: 0; overflow: hidden; transition: max-height .3s ease, padding .3s;
  font-size: 15px; color: var(--text-secondary); line-height: 1.8;
}
.faq-item.open .faq-a { max-height: 500px; padding-top: 12px; }

/* ── Legal Pages ──────────────────────────── */
.legal-hero {
  padding: calc(var(--header-h) + 60px) 0 40px;
  background: var(--bg-soft); text-align: center;
}
.legal-hero h1 { font-size: 36px; font-weight: 700; }
.legal-content {
  max-width: 800px; margin: 60px auto; padding: 0 24px;
  font-size: 15px; color: var(--text-secondary); line-height: 2;
  white-space: pre-wrap;
}

/* ── Mobile Nav Overlay ───────────────────── */
.mobile-nav {
  display: none; position: fixed; top: 0; left: 0; right: 0; bottom: 0;
  background: rgba(255,255,255,0.98); z-index: 999;
  flex-direction: column; align-items: center; justify-content: center; gap: 24px;
}
.mobile-nav.show { display: flex; }
.mobile-nav a { font-size: 20px; font-weight: 600; color: var(--text); }
.mobile-nav a.active { color: var(--primary); }
.mobile-nav-close {
  position: absolute; top: 20px; right: 20px;
  background: none; border: none; font-size: 28px; cursor: pointer; color: var(--text);
}

/* ── Responsive ───────────────────────────── */
@media (max-width: 768px) {
  .main-nav { display: none; }
  .mobile-toggle { display: flex; }

  .hero { padding: calc(var(--header-h) + 40px) 0 60px; }
  .hero-inner { flex-direction: column; gap: 40px; text-align: center; }
  .hero-text p { margin: 0 auto 24px; }

  .section { padding: 60px 0; }
  .section-header { margin-bottom: 40px; }

  .vpn-intro { flex-direction: column; gap: 30px; }
  .why-grid { grid-template-columns: 1fr; }
  .features-grid { grid-template-columns: 1fr; }
  
  .use-case-panel.active { flex-direction: column; gap: 24px; }
  .use-case-image { flex: none; width: 100%; }

  .footer-grid { grid-template-columns: 1fr 1fr; gap: 30px; }
  .footer-bottom { flex-direction: column; gap: 8px; text-align: center; }

  .download-panel.active { flex-direction: column; gap: 30px; }
  .download-device { flex: none; width: 100%; max-width: 280px; margin: 0 auto; }
}

@media (max-width: 480px) {
  .footer-grid { grid-template-columns: 1fr; }
  .platform-tabs { gap: 8px; }
  .platform-tab { padding: 10px 16px; font-size: 13px; }
}