/* ============ 设计变量：与 ArkOvpn 客户端保持一致 ============ */
:root {
  --accent: #ed9b40;
  --accent-start: #f5b544;
  --accent-end: #e89315;
  --accent-pressed: #d9862b;
  --accent-light: #fef3d6;

  --bg-primary: #f5f6f8;
  --bg-secondary: #ffffff;
  --bg-tertiary: #f0f1f4;
  --hairline: #e5e7eb;

  --text-primary: #1f2937;
  --text-secondary: #4b5563;
  --text-tertiary: #9ca3af;

  --radius-sm: 10px;
  --radius: 16px;
  --radius-lg: 24px;
  --radius-full: 999px;

  --shadow-sm: 0 1px 2px rgba(31, 41, 55, .04), 0 2px 8px rgba(31, 41, 55, .04);
  --shadow: 0 4px 12px rgba(31, 41, 55, .06), 0 12px 32px rgba(31, 41, 55, .06);
  --shadow-lg: 0 8px 24px rgba(31, 41, 55, .08), 0 24px 64px rgba(31, 41, 55, .1);

  --maxw: 1160px;
  --nav-h: 64px;

  --ease: cubic-bezier(.4, 0, .2, 1);
}

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

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.7;
  color: var(--text-primary);
  background: var(--bg-primary);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

h1, h2, h3, h4 { margin: 0; font-weight: 700; letter-spacing: -.02em; line-height: 1.25; }
p { margin: 0; }
a { color: inherit; text-decoration: none; }
ul { margin: 0; padding-left: 1.25em; }
img, svg { display: block; max-width: 100%; }

.container {
  width: 100%;
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px;
}

.gradient-text {
  background: linear-gradient(120deg, var(--accent-start), var(--accent-end));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

/* ============ 顶部导航 ============ */
.nav {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--nav-h);
  display: flex;
  align-items: center;
  background: rgba(245, 246, 248, .72);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  border-bottom: 1px solid transparent;
  transition: background .3s var(--ease), border-color .3s var(--ease), box-shadow .3s var(--ease);
}

.nav.is-scrolled {
  background: rgba(255, 255, 255, .88);
  border-bottom-color: var(--hairline);
  box-shadow: var(--shadow-sm);
}

.nav .container {
  display: flex;
  align-items: center;
  gap: 32px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 17px;
  font-weight: 700;
  letter-spacing: -.01em;
}

.brand-icon {
  flex: none;
  width: 32px;
  height: 32px;
  border-radius: 8px;
  filter: drop-shadow(0 2px 6px rgba(237, 155, 64, .25));
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
  margin-left: auto;
}

.nav-links a {
  padding: 8px 14px;
  border-radius: var(--radius-full);
  font-size: 14.5px;
  font-weight: 500;
  color: var(--text-secondary);
  transition: background .2s var(--ease), color .2s var(--ease);
}

/* 通用链接的 hover 需要用 :not(.btn) 排除按钮：
   .nav-links a:hover 与 .nav-links a.btn-primary 特异性相同（0,2,1），
   若不加排除，hover 时的灰白底色会盖掉按钮的渐变，而白字仍生效，导致文字看不清。 */
.nav-links a:not(.btn):hover { background: var(--bg-tertiary); color: var(--text-primary); }
.nav-links a:not(.btn).is-active { color: var(--text-primary); background: var(--bg-tertiary); }

.nav-links a.btn-primary {
  margin-left: 8px;
  height: 38px;
  padding: 0 20px;
  font-size: 14px;
  color: #fff;
}

.nav-links a.btn-primary:hover {
  background: linear-gradient(135deg, var(--accent-start), var(--accent-end));
  color: #fff;
  transform: translateY(-1px);
}

.nav-toggle {
  display: none;
  margin-left: auto;
  width: 40px;
  height: 40px;
  border: none;
  border-radius: 12px;
  background: transparent;
  cursor: pointer;
  color: var(--text-primary);
}

.nav-toggle svg { width: 22px; height: 22px; }

/* ============ 按钮 ============ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  height: 50px;
  padding: 0 28px;
  border: 1px solid transparent;
  border-radius: var(--radius-full);
  font-size: 15.5px;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  white-space: nowrap;
  transition: transform .2s var(--ease), box-shadow .3s var(--ease),
    background .2s var(--ease), border-color .2s var(--ease);
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent-start), var(--accent-end));
  color: #fff;
  box-shadow: 0 4px 14px rgba(237, 155, 64, .32);
}

.btn-primary:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(237, 155, 64, .42); }
.btn-primary:active { transform: translateY(0); }

.btn-ghost {
  background: var(--bg-secondary);
  color: var(--text-primary);
  border-color: var(--hairline);
}

.btn-ghost:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.btn-ghost:active { transform: translateY(0); }

/* ============ Hero ============ */
.hero {
  position: relative;
  padding: 104px 0 0;
  overflow: hidden;
  text-align: center;
}

.hero::before,
.hero::after {
  content: '';
  position: absolute;
  border-radius: 50%;
  pointer-events: none;
  filter: blur(60px);
}

.hero::before {
  width: 620px;
  height: 620px;
  top: -240px;
  left: 50%;
  transform: translateX(-50%);
  background: radial-gradient(circle, rgba(237, 155, 64, .2), transparent 68%);
}

.hero::after {
  width: 460px;
  height: 460px;
  top: 180px;
  right: -160px;
  background: radial-gradient(circle, rgba(100, 149, 237, .12), transparent 68%);
}

.hero .container { position: relative; }

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px 6px 6px;
  border-radius: var(--radius-full);
  background: var(--bg-secondary);
  border: 1px solid var(--hairline);
  box-shadow: var(--shadow-sm);
  font-size: 13.5px;
  color: var(--text-secondary);
  margin-bottom: 28px;
}

.hero-badge b {
  padding: 2px 10px;
  border-radius: var(--radius-full);
  background: var(--accent-light);
  color: var(--accent-pressed);
  font-size: 12.5px;
  font-weight: 700;
}

.hero h1 {
  font-size: clamp(40px, 6vw, 68px);
  letter-spacing: -.04em;
  line-height: 1.1;
  margin-bottom: 24px;
}

.hero-lead {
  font-size: 19px;
  line-height: 1.8;
  color: var(--text-secondary);
  max-width: 34em;
  margin: 0 auto 38px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  justify-content: center;
}

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 56px;
  justify-content: center;
  margin-top: 56px;
  padding-top: 32px;
  border-top: 1px solid var(--hairline);
}

.hero-meta div { font-size: 13px; color: var(--text-tertiary); }
.hero-meta strong {
  display: block;
  font-size: 22px;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: -.02em;
}

/* ============ 品牌视觉 ============ */
.showcase { margin-top: 68px; }

.showcase-art {
  width: min(820px, 100%);
  margin: 0 auto;
  filter: drop-shadow(0 20px 48px rgba(31, 41, 55, .08));
}

.orbit-spin {
  transform-origin: 400px 240px;
  animation: spin 44s linear infinite;
}

.orbit-spin-rev {
  transform-origin: 400px 240px;
  animation: spin 30s linear infinite reverse;
}

.node-pulse { animation: nodePulse 3.6s ease-in-out infinite; }
.node-pulse--b { animation-delay: 1.2s; }
.node-pulse--c { animation-delay: 2.4s; }

@keyframes spin { to { transform: rotate(360deg); } }
@keyframes nodePulse {
  0%, 100% { opacity: .28; }
  50% { opacity: 1; }
}

/* ============ 通用区块 ============ */
.section { padding: 96px 0; }
.section--alt { background: var(--bg-secondary); border-block: 1px solid var(--hairline); }

.section-head { max-width: 640px; margin-bottom: 56px; }
.section-head.center { margin-left: auto; margin-right: auto; text-align: center; }

.section-eyebrow {
  display: block;
  font-size: 13px;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--accent-pressed);
  margin-bottom: 12px;
}

.section-head h2 { font-size: clamp(28px, 3.8vw, 42px); letter-spacing: -.03em; }
.section-head p { margin-top: 14px; font-size: 17px; color: var(--text-secondary); }

/* ============ 特性卡片 ============ */
.features {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 20px;
}

.feature {
  padding: 34px;
  border-radius: var(--radius);
  background: var(--bg-primary);
  border: 1px solid var(--hairline);
  transition: transform .3s var(--ease), box-shadow .3s var(--ease), border-color .3s var(--ease);
}

.section--alt .feature { background: var(--bg-secondary); }

.feature:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow);
  border-color: transparent;
}

.feature-icon {
  width: 46px;
  height: 46px;
  border-radius: 14px;
  display: grid;
  place-items: center;
  background: var(--accent-light);
  color: var(--accent-pressed);
  margin-bottom: 18px;
}

.feature-icon svg { width: 22px; height: 22px; }
.feature h3 { font-size: 18.5px; margin-bottom: 8px; }
.feature p { font-size: 14.5px; color: var(--text-secondary); line-height: 1.75; }

/* 正文内链接 */
.feature p a,
.doc-body a {
  color: var(--accent-pressed);
  font-weight: 600;
  text-decoration: underline;
  text-decoration-color: rgba(217, 134, 43, .35);
  text-underline-offset: 3px;
  transition: text-decoration-color .2s var(--ease);
}

.feature p a:hover,
.doc-body a:hover { text-decoration-color: var(--accent-pressed); }

/* ============ 步骤 ============ */
.steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 32px;
  counter-reset: step;
}

.step::before {
  counter-increment: step;
  content: counter(step);
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border-radius: 12px;
  background: var(--text-primary);
  color: #fff;
  font-size: 15px;
  font-weight: 700;
  margin-bottom: 18px;
}

.step h3 { font-size: 17.5px; margin-bottom: 6px; }
.step p { font-size: 14.5px; color: var(--text-secondary); }

/* ============ 隐私承诺 ============ */
.pledge {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 28px;
  margin-top: 8px;
}

.pledge-item {
  padding-top: 20px;
  border-top: 2px solid var(--accent);
}

.pledge-item h4 { font-size: 16.5px; margin-bottom: 6px; }
.pledge-item p { font-size: 14px; color: var(--text-secondary); line-height: 1.75; }

/* ============ CTA ============ */
.cta {
  position: relative;
  overflow: hidden;
  padding: 76px 56px;
  border-radius: var(--radius-lg);
  background: linear-gradient(135deg, #232b37, #151a22);
  text-align: center;
  color: #fff;
}

.cta::before {
  content: '';
  position: absolute;
  width: 460px;
  height: 460px;
  top: -180px;
  right: -120px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(237, 155, 64, .34), transparent 66%);
  filter: blur(50px);
}

.cta::after {
  content: '';
  position: absolute;
  width: 380px;
  height: 380px;
  bottom: -180px;
  left: -100px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(100, 149, 237, .2), transparent 66%);
  filter: blur(50px);
}

.cta > * { position: relative; }
.cta h2 { font-size: clamp(26px, 3.6vw, 38px); margin-bottom: 14px; }
.cta p { color: rgba(255, 255, 255, .7); margin-bottom: 32px; font-size: 17px; }
.cta .hero-actions { justify-content: center; }

.cta .btn-ghost {
  background: rgba(255, 255, 255, .08);
  border-color: rgba(255, 255, 255, .18);
  color: #fff;
}

.cta .btn-ghost:hover { background: rgba(255, 255, 255, .14); }

/* ============ 文档页（隐私政策 / 用户协议） ============ */
.doc-hero { padding: 72px 0 8px; }
.doc-hero h1 { font-size: clamp(30px, 4vw, 44px); letter-spacing: -.03em; }

.doc-meta {
  margin-top: 16px;
  font-size: 14px;
  color: var(--text-tertiary);
}

.doc-layout {
  display: grid;
  grid-template-columns: 232px 1fr;
  gap: 56px;
  align-items: start;
  padding: 48px 0 96px;
}

.doc-toc {
  position: sticky;
  top: calc(var(--nav-h) + 28px);
  padding: 20px;
  border-radius: var(--radius);
  background: var(--bg-secondary);
  border: 1px solid var(--hairline);
}

.doc-toc-title {
  font-size: 12px;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--text-tertiary);
  margin-bottom: 12px;
}

.doc-toc a {
  display: block;
  padding: 7px 10px;
  border-radius: 9px;
  font-size: 14px;
  color: var(--text-secondary);
  transition: background .2s var(--ease), color .2s var(--ease);
}

.doc-toc a:hover { background: var(--bg-tertiary); color: var(--text-primary); }
.doc-toc a.is-active { background: var(--accent-light); color: var(--accent-pressed); font-weight: 600; }

.doc-body {
  background: var(--bg-secondary);
  border: 1px solid var(--hairline);
  border-radius: var(--radius);
  padding: 48px 52px;
}

.doc-body h2 {
  font-size: 22px;
  margin: 44px 0 14px;
  padding-top: 8px;
  scroll-margin-top: calc(var(--nav-h) + 24px);
}

.doc-body h2:first-of-type { margin-top: 0; }
.doc-body h3 { font-size: 17px; margin: 28px 0 10px; }

.doc-body p,
.doc-body li {
  font-size: 15.5px;
  line-height: 1.9;
  color: var(--text-secondary);
}

.doc-body p + p { margin-top: 14px; }
.doc-body ul { margin: 12px 0; }
.doc-body li { margin: 6px 0; }
.doc-body strong { color: var(--text-primary); font-weight: 600; }

.doc-note {
  margin: 0 0 28px;
  padding: 16px 20px;
  border-radius: var(--radius-sm);
  background: var(--accent-light);
  border-left: 3px solid var(--accent);
  font-size: 14.5px;
  color: var(--text-secondary);
  line-height: 1.8;
}

.doc-contact {
  margin-top: 40px;
  padding-top: 28px;
  border-top: 1px solid var(--hairline);
  font-size: 14.5px;
  color: var(--text-secondary);
}

/* ============ 页脚 ============ */
.footer {
  padding: 60px 0 40px;
  background: var(--bg-secondary);
  border-top: 1px solid var(--hairline);
}

/* 首列弹性占满剩余宽度，链接列按内容自适应，避免过宽导致一行放不下 */
.footer-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) repeat(3, auto);
  gap: 48px;
  padding-bottom: 36px;
}

.footer-about p {
  margin-top: 14px;
  font-size: 14px;
  color: var(--text-tertiary);
  max-width: 30em;
  line-height: 1.8;
}

.footer-col h4 {
  font-size: 13px;
  letter-spacing: .06em;
  text-transform: uppercase;
  color: var(--text-tertiary);
  margin-bottom: 14px;
}

.footer-col a {
  display: block;
  padding: 5px 0;
  font-size: 14.5px;
  color: var(--text-secondary);
  transition: color .2s var(--ease);
}

.footer-col a:hover { color: var(--accent-pressed); }

.footer-bottom {
  padding-top: 24px;
  border-top: 1px solid var(--hairline);
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: space-between;
  font-size: 13px;
  color: var(--text-tertiary);
}

/* ============ 响应式 ============ */
@media (max-width: 960px) {
  .hero { padding: 64px 0 0; }
  .hero-lead { max-width: none; }
  .doc-layout { grid-template-columns: 1fr; gap: 32px; }
  .doc-toc { position: static; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .section { padding: 72px 0; }
}

@media (max-width: 720px) {
  .nav-links {
    position: absolute;
    top: var(--nav-h);
    left: 16px;
    right: 16px;
    flex-direction: column;
    align-items: stretch;
    gap: 4px;
    padding: 12px;
    border-radius: var(--radius);
    background: var(--bg-secondary);
    border: 1px solid var(--hairline);
    box-shadow: var(--shadow);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-8px);
    transition: opacity .25s var(--ease), transform .25s var(--ease), visibility .25s;
  }

  .nav-links.is-open { opacity: 1; visibility: visible; transform: translateY(0); }
  .nav-links a.btn-primary { margin-left: 0; margin-top: 6px; }
  .nav-toggle { display: grid; place-items: center; }

  .hero-meta { gap: 32px; }
  .doc-body { padding: 32px 24px; }
  .cta { padding: 52px 28px; }
  .footer-grid { grid-template-columns: 1fr; gap: 28px; }
}

@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: .01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: .01ms !important;
  }
  html { scroll-behavior: auto; }
}