/* ================================================================
   NetShield VPN — 全局样式表
   移动端优先 (375px) → 768px → 1024px → 1440px
   色彩系统：深色主题 + 青蓝渐变 + 琥珀暖锚 + 玻璃卡片
   WCAG AA 合规
   ================================================================ */

/* ---------- CSS Custom Properties ---------- */
:root {
  /* 主色系 */
  --color-bg:        #080C14;
  --color-bg-raised: #0D1321;
  --color-surface:   rgba(255, 255, 255, 0.03);
  --color-border:    rgba(255, 255, 255, 0.06);
  --color-border-hover: rgba(255, 255, 255, 0.12);

  /* 品牌渐变 */
  --color-primary:   #2563EB;
  --color-cyan:      #06B6D4;
  --gradient-brand:  linear-gradient(135deg, #2563EB 0%, #06B6D4 100%);
  --gradient-text:   linear-gradient(135deg, #3B82F6 0%, #06B6D4 50%, #22D3EE 100%);

  /* 暖色锚点 */
  --color-accent:    #F59E0B;
  --color-accent-glow: rgba(245, 158, 11, 0.25);

  /* Windows & Android 品牌色 */
  --color-win:       #3B82F6;
  --color-android:   #22C55E;

  /* 文字层级 */
  --text-heading:    #F1F5F9;
  --text-body:       #CBD5E1;      /* WCAG AA 4.6:1 on #080C14 */
  --text-muted:      #94A3B8;
  --text-dim:        #64748B;

  /* 排版 */
  --font-sans:       'Inter', 'SF Pro Display', 'Segoe UI', system-ui, -apple-system, sans-serif;
  --font-mono:       'JetBrains Mono', 'Fira Code', 'Cascadia Code', monospace;
  --lh-body:         1.75;
  --lh-heading:      1.2;

  /* 间距 */
  --space-xs:        4px;
  --space-sm:        8px;
  --space-md:        16px;
  --space-lg:        24px;
  --space-xl:        32px;
  --space-2xl:       48px;
  --space-3xl:       64px;
  --space-4xl:       96px;

  /* 圆角 */
  --radius-sm:       8px;
  --radius-md:       12px;
  --radius-lg:       16px;
  --radius-xl:       24px;
  --radius-full:     9999px;

  /* 阴影 */
  --shadow-card:     0 1px 2px rgba(0, 0, 0, 0.4), 0 4px 16px rgba(0, 0, 0, 0.3);
  --shadow-glow:     0 0 40px rgba(37, 99, 235, 0.15), 0 0 80px rgba(6, 182, 212, 0.08);
  --shadow-popular:  0 0 32px rgba(37, 99, 235, 0.25), 0 8px 32px rgba(0, 0, 0, 0.4);

  /* 过渡 */
  --ease-out:        cubic-bezier(0.16, 1, 0.3, 1);
  --ease-in-out:     cubic-bezier(0.65, 0, 0.35, 1);
  --duration-fast:   150ms;
  --duration-base:   300ms;
  --duration-slow:   600ms;

  /* 导航高度 */
  --nav-h:           56px;
}

/* ---------- Reset & Base ---------- */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: var(--nav-h);
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: var(--lh-body);
  color: var(--text-body);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

img, svg { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
ul, ol { list-style: none; }
button { font: inherit; cursor: pointer; border: none; background: none; color: inherit; }

::selection {
  background: rgba(37, 99, 235, 0.35);
  color: #fff;
}

/* ---------- Typography ---------- */
h1, h2, h3, h4 { color: var(--text-heading); line-height: var(--lh-heading); }
h1 { font-size: clamp(2rem, 5vw, 3.5rem); font-weight: 800; letter-spacing: -0.02em; }
h2 { font-size: clamp(1.5rem, 4vw, 2.5rem); font-weight: 700; letter-spacing: -0.01em; }
h3 { font-size: 1.125rem; font-weight: 600; }
h4 { font-size: 1rem; font-weight: 600; }

.gradient-text {
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  font-weight: 600;
  border-radius: var(--radius-full);
  transition: all var(--duration-base) var(--ease-out);
  white-space: nowrap;
  cursor: pointer;
  position: relative;
  overflow: hidden;
}

.btn--sm  { padding: 8px 20px; font-size: 0.875rem; }
.btn--lg  { padding: 14px 32px; font-size: 1rem; }
.btn--full { width: 100%; padding: 14px 24px; font-size: 1rem; }

.btn--primary {
  background: var(--gradient-brand);
  color: #fff;
  box-shadow: 0 2px 8px rgba(37, 99, 235, 0.3);
}
.btn--primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 20px rgba(37, 99, 235, 0.45);
}
.btn--primary:active { transform: translateY(0); }

.btn--ghost {
  background: transparent;
  color: var(--text-body);
  border: 1px solid var(--color-border);
}
.btn--ghost:hover {
  border-color: var(--color-border-hover);
  color: var(--text-heading);
  background: rgba(255,255,255,0.04);
}

.btn--outline {
  background: transparent;
  color: var(--text-heading);
  border: 1.5px solid var(--color-border-hover);
}
.btn--outline:hover {
  border-color: var(--color-primary);
  background: rgba(37, 99, 235, 0.08);
}

/* ---------- Navigation ---------- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  height: var(--nav-h);
  transition: background var(--duration-base), box-shadow var(--duration-base);
}
.nav--scrolled {
  background: rgba(8, 12, 20, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  box-shadow: 0 1px 0 var(--color-border);
}
.nav__inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: 0 var(--space-lg);
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav__logo {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-weight: 700;
  font-size: 1.125rem;
  color: var(--text-heading);
}
.nav__logo-text { background: var(--gradient-text); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
.nav__links { display: none; }
.nav__links .nav__link {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--text-muted);
  transition: color var(--duration-fast);
}
.nav__links .nav__link:hover { color: var(--text-heading); }
.nav__actions { display: flex; align-items: center; gap: var(--space-md); }
.nav__actions .btn { display: none; }

/* 汉堡菜单 */
.nav__burger {
  display: flex;
  flex-direction: column;
  gap: 5px;
  padding: 4px;
  z-index: 1001;
}
.nav__burger span {
  display: block;
  width: 22px;
  height: 2px;
  background: var(--text-heading);
  border-radius: 2px;
  transition: all var(--duration-base) var(--ease-out);
}
.nav__burger.active span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.nav__burger.active span:nth-child(2) { opacity: 0; }
.nav__burger.active span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

/* 移动端菜单 */
.nav__mobile {
  position: fixed;
  inset: 0;
  z-index: 999;
  background: rgba(8, 12, 20, 0.97);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: var(--space-xl);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--duration-base);
}
.nav__mobile.active {
  opacity: 1;
  pointer-events: auto;
}
.nav__mobile a {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-heading);
  transition: color var(--duration-fast);
}
.nav__mobile a:hover { color: var(--color-cyan); }

/* ====== Screen 1 — Hero ====== */
.hero {
  position: relative;
  min-height: 100vh;
  min-height: 100dvh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: calc(var(--nav-h) + var(--space-3xl)) var(--space-lg) var(--space-3xl);
  overflow: hidden;
}

/* Canvas 地球背景 */
.hero__globe {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  z-index: 0;
  opacity: 0.35;
}
@media (max-width: 1023px) {
  .hero__globe { display: none; }
}

.hero__content {
  position: relative;
  z-index: 1;
  max-width: 720px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-lg);
}

.hero__badge {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: 6px 16px;
  border-radius: var(--radius-full);
  background: rgba(37, 99, 235, 0.1);
  border: 1px solid rgba(37, 99, 235, 0.2);
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--color-cyan);
}
.hero__badge-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--color-cyan);
  box-shadow: 0 0 8px var(--color-cyan);
  animation: pulse-dot 2s ease-in-out infinite;
}

.hero__title {
  font-size: clamp(2rem, 7vw, 3.75rem);
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.025em;
}
.hero__title-gradient {
  display: block;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero__subtitle {
  font-size: clamp(0.9375rem, 2vw, 1.125rem);
  color: var(--text-muted);
  max-width: 560px;
  line-height: 1.7;
}

.hero__cta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-md);
  justify-content: center;
}

.hero__platforms {
  display: flex;
  gap: var(--space-lg);
  padding-top: var(--space-sm);
}
.hero__platform {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.8125rem;
  font-weight: 500;
  color: var(--text-muted);
}
.hero__platform svg { opacity: 0.6; }

.hero__note {
  font-size: 0.75rem;
  color: var(--text-dim);
}

.hero__scroll {
  position: absolute;
  bottom: var(--space-xl);
  left: 50%;
  transform: translateX(-50%);
  color: var(--text-dim);
  animation: bounce 2s ease-in-out infinite;
  z-index: 1;
}

/* ====== Screen 2 — Trust Bar ====== */
.trust {
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
  background: var(--color-bg-raised);
}
.trust__inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: var(--space-xl) var(--space-lg);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-lg);
}
.trust__stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-lg) var(--space-xl);
  width: 100%;
}
.trust__stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
}
.trust__stat-value {
  font-size: clamp(1.5rem, 4vw, 2.25rem);
  font-weight: 800;
  background: var(--gradient-text);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  font-variant-numeric: tabular-nums;
}
.trust__stat-label {
  font-size: 0.8125rem;
  color: var(--text-muted);
}
.trust__audit {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-sm);
}
.trust__audit-label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-dim);
}
.trust__audit-logos {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 1.125rem;
  font-weight: 600;
  color: var(--text-muted);
}
.trust__audit-sep { color: var(--text-dim); }

/* ====== Screen 3 — Features ====== */
.features {
  max-width: 1280px;
  margin: 0 auto;
  padding: var(--space-4xl) var(--space-lg);
}
.features__header {
  text-align: center;
  margin-bottom: var(--space-3xl);
}
.features__title { margin-bottom: var(--space-sm); }
.features__subtitle { color: var(--text-muted); font-size: 1rem; max-width: 480px; margin: 0 auto; }

.features__group {
  margin-bottom: var(--space-3xl);
}
.features__group:last-child { margin-bottom: 0; }

.features__group-title {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 1rem;
  font-weight: 600;
  color: var(--text-heading);
  margin-bottom: var(--space-lg);
  padding-bottom: var(--space-md);
  border-bottom: 1px solid var(--color-border);
}
.features__group-title svg { flex-shrink: 0; }

.features__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
}

/* 功能卡片 */
.feature-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  transition: border-color var(--duration-base), transform var(--duration-base), box-shadow var(--duration-base);
}
.feature-card:hover {
  border-color: var(--color-border-hover);
  transform: translateY(-2px);
  box-shadow: var(--shadow-card);
}
.feature-card__icon {
  width: 48px;
  height: 48px;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-md);
  background: rgba(37, 99, 235, 0.1);
  color: var(--color-cyan);
}
.feature-card--win .feature-card__icon { background: rgba(59, 130, 246, 0.1); color: var(--color-win); }
.feature-card--android .feature-card__icon { background: rgba(34, 197, 94, 0.1); color: var(--color-android); }

.feature-card__title {
  font-size: 1.0625rem;
  font-weight: 600;
  margin-bottom: var(--space-sm);
}
.feature-card__desc {
  font-size: 0.9375rem;
  color: var(--text-muted);
  line-height: 1.65;
}

/* ====== Screen 4 — Servers ====== */
.servers {
  padding: var(--space-4xl) var(--space-lg);
  background: var(--color-bg-raised);
}
.servers__header {
  text-align: center;
  margin-bottom: var(--space-2xl);
}
.servers__subtitle { color: var(--text-muted); margin-top: var(--space-sm); }

.servers__body {
  max-width: 1280px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-2xl);
}

.servers__globe {
  width: 100%;
  max-width: 500px;
  aspect-ratio: 4/3;
  display: flex;
  align-items: center;
  justify-content: center;
}
.servers__globe-fallback { width: 100%; height: auto; }
.servers__globe canvas { width: 100%; height: 100%; }

.servers__list {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-sm);
  width: 100%;
}
.server-node {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-md) var(--space-lg);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  transition: border-color var(--duration-fast);
}
.server-node:hover { border-color: var(--color-border-hover); }
.server-node__loc {
  display: flex;
  align-items: center;
  gap: var(--space-md);
}
.server-node__flag { font-size: 1.25rem; width: 28px; text-align: center; }
.server-node__city { font-weight: 500; color: var(--text-heading); font-size: 0.9375rem; }
.server-node__country { font-size: 0.8125rem; color: var(--text-dim); }
.server-node__meta { text-align: right; }
.server-node__load {
  font-size: 0.75rem;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: var(--radius-full);
}
.server-node__load--low  { color: #22C55E; background: rgba(34,197,94,0.1); }
.server-node__load--mid  { color: var(--color-accent); background: rgba(245,158,11,0.1); }
.server-node__load--high { color: #EF4444; background: rgba(239,68,68,0.1); }
.server-node__ms { font-size: 0.75rem; color: var(--text-dim); margin-top: 2px; }

/* ====== Screen 5 — Security + Pricing ====== */
.sec-pricing {
  padding: var(--space-4xl) var(--space-lg);
  max-width: 1280px;
  margin: 0 auto;
}

/* ---- 安全 ---- */
.security { margin-bottom: var(--space-4xl); }
.security__title { text-align: center; margin-bottom: var(--space-2xl); }
.security__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-md);
}
.security__item {
  padding: var(--space-lg);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  transition: border-color var(--duration-fast);
}
.security__item:hover { border-color: var(--color-border-hover); }
.security__item h4 {
  font-size: 0.9375rem;
  margin-bottom: var(--space-xs);
  color: var(--text-heading);
}
.security__item p {
  font-size: 0.875rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* ---- 定价 ---- */
.pricing__title { text-align: center; margin-bottom: var(--space-sm); }
.pricing__subtitle { text-align: center; color: var(--text-muted); font-size: 0.9375rem; margin-bottom: var(--space-2xl); }

.pricing__cards {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
  align-items: center;
  max-width: 1100px;
  margin: 0 auto;
}

.pricing-card {
  position: relative;
  width: 100%;
  max-width: 380px;
  background: var(--color-bg-raised);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-2xl) var(--space-xl);
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  transition: transform var(--duration-base), border-color var(--duration-base), box-shadow var(--duration-base);
}
.pricing-card:hover {
  border-color: var(--color-border-hover);
  transform: translateY(-4px);
}

.pricing-card--popular {
  border-color: rgba(37, 99, 235, 0.35);
  box-shadow: var(--shadow-popular);
  transform: scale(1.02);
}
.pricing-card--popular:hover { transform: scale(1.02) translateY(-4px); }

.pricing-card--best {
  border-color: rgba(245, 158, 11, 0.3);
}

.pricing-card__badge {
  position: absolute;
  top: -13px;
  left: 50%;
  transform: translateX(-50%);
  padding: 4px 16px;
  border-radius: var(--radius-full);
  font-size: 0.8125rem;
  font-weight: 700;
  white-space: nowrap;
}
.pricing-card--popular .pricing-card__badge {
  background: var(--gradient-brand);
  color: #fff;
  box-shadow: 0 2px 12px rgba(37, 99, 235, 0.4);
}
.pricing-card--best .pricing-card__badge {
  background: var(--color-accent);
  color: #000;
  box-shadow: 0 2px 12px var(--color-accent-glow);
}

.pricing-card__name { font-size: 1.25rem; margin-bottom: 4px; }
.pricing-card__desc { font-size: 0.875rem; color: var(--text-muted); margin-bottom: var(--space-lg); }

.pricing-card__price {
  display: flex;
  align-items: baseline;
  margin-bottom: var(--space-sm);
}
.pricing-card__currency { font-size: 1.25rem; font-weight: 600; color: var(--text-muted); }
.pricing-card__amount {
  font-size: 3rem;
  font-weight: 800;
  color: var(--text-heading);
  line-height: 1;
  margin: 0 2px;
}
.pricing-card__period { font-size: 1rem; color: var(--text-muted); }
.pricing-card__billed { font-size: 0.8rem; color: var(--text-dim); margin-bottom: var(--space-lg); }

.pricing-card__features {
  width: 100%;
  text-align: left;
  margin-bottom: var(--space-xl);
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}
.pricing-card__features li {
  font-size: 0.875rem;
  color: var(--text-muted);
  padding-left: 24px;
  position: relative;
}
.pricing-card__features li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 6px;
  width: 14px;
  height: 14px;
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' fill='none'%3E%3Cpath d='M3 8l3.5 3.5L13 5' stroke='%2306B6D4' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E") no-repeat center;
  background-size: contain;
}

/* ====== Download ====== */
.download {
  padding: var(--space-4xl) var(--space-lg);
  background: var(--color-bg-raised);
  border-top: 1px solid var(--color-border);
}
.download__title { text-align: center; margin-bottom: var(--space-sm); }
.download__subtitle { text-align: center; color: var(--text-muted); font-size: 0.9375rem; margin-bottom: var(--space-2xl); max-width: 480px; margin-left: auto; margin-right: auto; }

.download__cards {
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
  align-items: center;
  max-width: 800px;
  margin: 0 auto var(--space-xl);
}

.download-card {
  position: relative;
  width: 100%;
  max-width: 380px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: var(--space-2xl) var(--space-xl);
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  transition: border-color var(--duration-base), transform var(--duration-base), box-shadow var(--duration-base);
}
.download-card:hover {
  border-color: var(--color-border-hover);
  transform: translateY(-4px);
  box-shadow: var(--shadow-card);
}

.download-card--win  { border-top: 3px solid var(--color-win); }
.download-card--android { border-top: 3px solid var(--color-android); }

.download-card__icon {
  width: 72px;
  height: 72px;
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-lg);
}
.download-card--win .download-card__icon  { background: rgba(59, 130, 246, 0.1); color: var(--color-win); }
.download-card--android .download-card__icon { background: rgba(34, 197, 94, 0.1); color: var(--color-android); }

.download-card__name { font-size: 1.375rem; font-weight: 700; margin-bottom: 2px; }
.download-card__ver  { font-size: 0.8125rem; color: var(--text-dim); margin-bottom: var(--space-lg); }

.download-card__perks {
  width: 100%;
  text-align: left;
  margin-bottom: var(--space-xl);
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}
.download-card__perks li {
  font-size: 0.875rem;
  color: var(--text-muted);
  padding-left: 24px;
  position: relative;
}
.download-card__perks li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 6px;
  width: 14px;
  height: 14px;
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16' fill='none'%3E%3Cpath d='M3 8l3.5 3.5L13 5' stroke='%2306B6D4' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E") no-repeat center;
  background-size: contain;
}

.download-card__hash {
  font-size: 0.75rem;
  color: var(--text-dim);
  margin-top: var(--space-md);
  font-family: var(--font-mono);
}

.download__notice {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  font-size: 0.8125rem;
  color: var(--text-dim);
  max-width: 520px;
  margin: 0 auto;
  text-align: center;
}
.download__notice svg { flex-shrink: 0; color: var(--color-accent); }

/* ====== Screen 6 — FAQ ====== */
.faq-section {
  max-width: 800px;
  margin: 0 auto;
  padding: var(--space-4xl) var(--space-lg);
}
.faq-section__title { text-align: center; margin-bottom: var(--space-2xl); }

.faq-section__list {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.faq-item {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color var(--duration-fast);
}
.faq-item:hover { border-color: var(--color-border-hover); }
.faq-item[open] { border-color: rgba(37, 99, 235, 0.2); }

.faq-item__q {
  padding: var(--space-lg);
  font-weight: 600;
  font-size: 0.9375rem;
  color: var(--text-heading);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-md);
  user-select: none;
}
.faq-item__q::after {
  content: '';
  flex-shrink: 0;
  width: 20px;
  height: 20px;
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 20 20' fill='none'%3E%3Cpath d='M5 7.5l5 5 5-5' stroke='%2394A3B8' stroke-width='1.5' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E") no-repeat center;
  transition: transform var(--duration-base);
}
.faq-item[open] .faq-item__q::after { transform: rotate(180deg); }

.faq-item__a {
  padding: 0 var(--space-lg) var(--space-lg);
  font-size: 0.9375rem;
  color: var(--text-muted);
  line-height: 1.7;
}
.faq-item__a p { margin: 0; }

/* ====== Footer ====== */
.footer {
  border-top: 1px solid var(--color-border);
  background: var(--color-bg-raised);
  padding: var(--space-3xl) var(--space-lg) var(--space-xl);
}
.footer__inner {
  max-width: 1280px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: var(--space-2xl);
  margin-bottom: var(--space-2xl);
}
.footer__brand { display: flex; flex-direction: column; gap: var(--space-md); }
.footer__tagline { font-size: 0.875rem; color: var(--text-dim); max-width: 280px; }
.footer__links { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--space-lg); }
.footer__col { display: flex; flex-direction: column; gap: var(--space-sm); }
.footer__col h4 { font-size: 0.8125rem; text-transform: uppercase; letter-spacing: 0.05em; color: var(--text-dim); margin-bottom: 4px; }
.footer__col a { font-size: 0.875rem; color: var(--text-muted); transition: color var(--duration-fast); }
.footer__col a:hover { color: var(--text-heading); }

.footer__bottom {
  max-width: 1280px;
  margin: 0 auto;
  padding-top: var(--space-lg);
  border-top: 1px solid var(--color-border);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-md);
}
.footer__bottom p { font-size: 0.8125rem; color: var(--text-dim); text-align: center; }
.footer__legal { display: flex; gap: var(--space-lg); }
.footer__legal a { font-size: 0.8125rem; color: var(--text-dim); transition: color var(--duration-fast); }
.footer__legal a:hover { color: var(--text-muted); }

/* ====== Animations ====== */
@keyframes pulse-dot {
  0%, 100% { box-shadow: 0 0 4px var(--color-cyan); }
  50%      { box-shadow: 0 0 14px var(--color-cyan), 0 0 24px rgba(6, 182, 212, 0.3); }
}
@keyframes bounce {
  0%, 100% { transform: translateX(-50%) translateY(0); }
  50%      { transform: translateX(-50%) translateY(8px); }
}

/* 滚动渐显 */
.fade-up {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity var(--duration-slow) var(--ease-out),
              transform var(--duration-slow) var(--ease-out);
}
.fade-up.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Stagger children */
.stagger > * { opacity: 0; transform: translateY(18px); }
.stagger > *.visible {
  opacity: 1;
  transform: translateY(0);
  transition: opacity 0.5s var(--ease-out), transform 0.5s var(--ease-out);
}

/* ====== Reduced Motion ====== */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  html { scroll-behavior: auto; }
  .fade-up, .stagger > * { opacity: 1; transform: none; }
  .hero__globe { display: none; }
}

/* ================================================================
   RESPONSIVE BREAKPOINTS
   ================================================================ */

/* ---------- 480px+ — 小屏手机横屏 ---------- */
@media (min-width: 480px) {
  .trust__stats { grid-template-columns: repeat(4, 1fr); }
}

/* ---------- 640px+ ---------- */
@media (min-width: 640px) {
  .features__grid--3col { grid-template-columns: repeat(2, 1fr); }
  .security__grid { grid-template-columns: repeat(2, 1fr); }
  .servers__list { grid-template-columns: repeat(2, 1fr); }
  .pricing__cards { flex-direction: row; flex-wrap: wrap; justify-content: center; }
  .pricing-card { max-width: 320px; }
  .download__cards { flex-direction: row; justify-content: center; }
  .download-card { max-width: 360px; }
}

/* ---------- 768px+ — 平板 ---------- */
@media (min-width: 768px) {
  :root { --nav-h: 64px; }

  .nav__links { display: flex; align-items: center; gap: var(--space-xl); }
  .nav__actions .btn { display: inline-flex; }
  .nav__burger { display: none; }

  .trust__inner { flex-direction: row; justify-content: space-between; padding: var(--space-xl) var(--space-2xl); }
  .trust__stats { width: auto; gap: var(--space-2xl); }
  .trust__stat { align-items: flex-start; }
  .trust__audit { align-items: flex-end; }

  .features__grid--3col { grid-template-columns: repeat(3, 1fr); }

  .servers__body { flex-direction: row; align-items: flex-start; }
  .servers__globe { flex: 1; }
  .servers__list { flex: 1; }

  .security__grid { grid-template-columns: repeat(3, 1fr); }

  .footer__inner { flex-direction: row; justify-content: space-between; }
  .footer__bottom { flex-direction: row; justify-content: space-between; }
  .footer__links { grid-template-columns: repeat(3, 120px); }
}

/* ---------- 1024px+ — 桌面 ---------- */
@media (min-width: 1024px) {
  .hero__globe { display: block; }
  .pricing-card--popular { transform: scale(1.05); }
  .pricing-card--popular:hover { transform: scale(1.05) translateY(-4px); }

  .servers__body { gap: var(--space-3xl); }
  .servers__globe { max-width: 520px; }
}

/* ---------- 1280px+ — 大屏 ---------- */
@media (min-width: 1280px) {
  .features { padding-left: var(--space-4xl); padding-right: var(--space-4xl); }
}