/* =============================================================
   快连 VPN / LetsVPN — 站点样式（全新设计，不依赖官网样式）
   全部使用 px + 媒体查询，不使用 rem，避免根字号缩放带来的失控
   ============================================================= */

:root {
  --brand: #6c3bff;
  --brand-2: #9b5cff;
  --brand-3: #3b5bff;
  --ink: #0d0d1a;
  --text: #14142b;
  --text-2: #5a6178;
  --text-3: #8b93a7;
  --line: #e7e9f2;
  --bg: #ffffff;
  --bg-soft: #f6f7fb;
  --shadow: 0 4px 24px rgba(24, 20, 60, .07);
  --shadow-lg: 0 18px 48px rgba(24, 20, 60, .12);
  --head-h: 64px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", "Segoe UI",
               system-ui, -apple-system, "Helvetica Neue", Arial, sans-serif;
  font-size: 15px;
  line-height: 1.7;
  color: var(--text);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; display: block; border: 0; }
a { color: inherit; text-decoration: none; transition: color .18s, opacity .18s, background .18s, border-color .18s, transform .18s; }
button { font: inherit; cursor: pointer; }
ul, ol { margin: 0; padding: 0; list-style: none; }
h1, h2, h3, h4 { margin: 0; font-weight: 700; line-height: 1.3; letter-spacing: -.01em; }
p { margin: 0; }
:focus-visible { outline: 2px solid var(--brand); outline-offset: 3px; border-radius: 6px; }

.wrap { width: 100%; max-width: 1180px; margin: 0 auto; padding: 0 24px; }

/* ============================ 顶栏 ============================ */
.head {
  position: fixed; inset: 0 0 auto; z-index: 100;
  height: var(--head-h);
  background: rgba(255, 255, 255, .82);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid transparent;
  transition: background .25s, border-color .25s, box-shadow .25s;
}
.head.is-solid { background: rgba(255, 255, 255, .95); border-bottom-color: var(--line); box-shadow: 0 2px 16px rgba(24, 20, 60, .05); }
.head .wrap { height: 100%; display: flex; align-items: center; gap: 28px; }
.head-logo { display: flex; align-items: center; flex-shrink: 0; }
.head-logo img {
  height: 32px; width: auto;
  /* 官方 logo 是位图（218×58），接近原始像素比例显示 + Chromium 对比度优化，边缘更实 */
  image-rendering: -webkit-optimize-contrast;
}
.head-nav { display: flex; align-items: center; gap: 4px; margin-left: auto; }
.head-nav a {
  padding: 8px 14px; border-radius: 10px; font-size: 14.5px; color: var(--text-2); font-weight: 500;
}
.head-nav a:hover { color: var(--text); background: var(--bg-soft); }
.head-nav a.is-active { color: var(--brand); background: rgba(108, 59, 255, .08); }
.head-actions { display: flex; align-items: center; gap: 12px; flex-shrink: 0; }

.lang { position: relative; }
.lang-btn {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 7px 10px 7px 12px; border: 1px solid var(--line); border-radius: 999px;
  background: #fff; font-size: 13.5px; color: var(--text-2);
}
.lang-btn:hover { border-color: #d6d9e6; color: var(--text); }
.lang-btn .caret { width: 7px; height: 7px; border-right: 1.5px solid currentColor; border-bottom: 1.5px solid currentColor; transform: rotate(45deg) translateY(-2px); }
.lang-menu {
  position: absolute; right: 0; top: calc(100% + 8px); min-width: 132px;
  background: #fff; border: 1px solid var(--line); border-radius: 12px; box-shadow: var(--shadow-lg);
  padding: 6px; display: none;
}
.lang.open .lang-menu { display: block; }
.lang-menu a {
  display: flex; align-items: center; justify-content: space-between; gap: 10px;
  padding: 8px 12px; border-radius: 8px; font-size: 14px; color: var(--text-2);
}
.lang-menu a:hover { background: var(--bg-soft); color: var(--text); }
.lang-menu a.on { color: var(--brand); font-weight: 600; }
.lang-menu a.on::after { content: ""; width: 6px; height: 6px; border-radius: 50%; background: var(--brand); }

.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 10px 20px; border-radius: 10px; border: 1px solid transparent;
  font-size: 14.5px; font-weight: 600; white-space: nowrap;
}
.btn-primary { background: linear-gradient(120deg, var(--brand), var(--brand-3)); color: #fff; box-shadow: 0 6px 18px rgba(108, 59, 255, .28); }
.btn-primary:hover { transform: translateY(-1px); box-shadow: 0 10px 26px rgba(108, 59, 255, .34); color: #fff; }
.btn-ghost { background: #fff; color: var(--text); border-color: var(--line); }
.btn-ghost:hover { border-color: #d6d9e6; background: #fcfcfe; }
.btn-dark { background: rgba(255, 255, 255, .1); color: #fff; border-color: rgba(255, 255, 255, .22); backdrop-filter: blur(6px); }
.btn-dark:hover { background: rgba(255, 255, 255, .18); color: #fff; }
.btn-lg { padding: 14px 28px; font-size: 16px; border-radius: 12px; }

.burger { display: none; width: 40px; height: 40px; border: 1px solid var(--line); border-radius: 10px; background: #fff; align-items: center; justify-content: center; }
.burger span { display: block; width: 17px; height: 1.8px; background: var(--text); border-radius: 2px; position: relative; transition: .25s; }
.burger span::before, .burger span::after { content: ""; position: absolute; left: 0; width: 17px; height: 1.8px; background: var(--text); border-radius: 2px; transition: .25s; }
.burger span::before { top: -5.5px; }
.burger span::after { top: 5.5px; }
.burger.on span { background: transparent; }
.burger.on span::before { top: 0; transform: rotate(45deg); }
.burger.on span::after { top: 0; transform: rotate(-45deg); }

/* ============================ 首屏 ============================ */
.hero {
  position: relative; overflow: hidden;
  padding: calc(var(--head-h) + 84px) 0 96px;
  background:
    radial-gradient(900px 460px at 82% 6%, rgba(155, 92, 255, .38), transparent 62%),
    radial-gradient(760px 420px at 12% 22%, rgba(59, 91, 255, .32), transparent 60%),
    linear-gradient(168deg, #14142b 0%, #0d0d1a 58%, #10102a 100%);
  color: #fff;
}
.hero::after {
  content: ""; position: absolute; inset: 0; pointer-events: none; opacity: .35;
  background-image: radial-gradient(rgba(255, 255, 255, .14) 1px, transparent 1px);
  background-size: 26px 26px;
  -webkit-mask-image: radial-gradient(70% 60% at 50% 30%, #000, transparent 75%);
          mask-image: radial-gradient(70% 60% at 50% 30%, #000, transparent 75%);
}
.hero .wrap { position: relative; z-index: 2; display: grid; grid-template-columns: 1.05fr .95fr; gap: 56px; align-items: center; }
.hero-eyebrow {
  display: inline-flex; align-items: center; gap: 14px; flex-wrap: wrap;
  padding: 7px 16px 7px 8px; border-radius: 999px;
  background: rgba(255, 255, 255, .08); border: 1px solid rgba(255, 255, 255, .14);
  font-size: 13px; color: rgba(255, 255, 255, .82); margin-bottom: 26px;
}
.hero-eyebrow b { color: #fff; font-size: 15px; font-weight: 700; }
.hero-eyebrow i { font-style: normal; opacity: .5; }
.hero h1 { font-size: 54px; line-height: 1.16; letter-spacing: -.02em; }
.hero h1 em {
  font-style: normal;
  background: linear-gradient(96deg, #b78bff, #7f9bff);
  -webkit-background-clip: text; background-clip: text; color: transparent;
}
.hero-sub { margin-top: 22px; font-size: 17px; line-height: 1.85; color: rgba(255, 255, 255, .72); max-width: 520px; }
.hero-cta { display: flex; flex-wrap: wrap; gap: 14px; margin-top: 36px; }
.hero-metrics { display: flex; gap: 44px; margin-top: 46px; padding-top: 30px; border-top: 1px solid rgba(255, 255, 255, .12); }
.hero-metrics div b { display: block; font-size: 32px; font-weight: 800; letter-spacing: -.02em; line-height: 1.2; }
.hero-metrics div span { font-size: 13.5px; color: rgba(255, 255, 255, .6); }
.hero-visual { position: relative; display: flex; justify-content: center; }
.hero-visual img { width: 100%; max-width: 520px; filter: drop-shadow(0 30px 60px rgba(0, 0, 0, .45)); }
.hero-glow {
  position: absolute; inset: 12% -6% -8%; z-index: -1; border-radius: 50%;
  background: radial-gradient(closest-side, rgba(124, 92, 255, .5), transparent 72%);
  filter: blur(24px);
}

/* ============================ 通用区块 ============================ */
.section { padding: 96px 0; }
.section-soft { background: var(--bg-soft); }
.section-dark { background: var(--ink); color: #fff; }
.sec-head { text-align: center; max-width: 720px; margin: 0 auto 52px; }
.sec-head .kicker {
  display: inline-block; margin-bottom: 14px; padding: 5px 13px; border-radius: 999px;
  background: rgba(108, 59, 255, .09); color: var(--brand); font-size: 13px; font-weight: 600; letter-spacing: .04em;
}
.section-dark .sec-head .kicker { background: rgba(255, 255, 255, .1); color: #c4b5fd; }
.sec-head h2 { font-size: 38px; letter-spacing: -.02em; }
.sec-head p { margin-top: 16px; font-size: 16px; color: var(--text-2); }
.section-dark .sec-head p { color: rgba(255, 255, 255, .66); }

.grid { display: grid; gap: 22px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }

/* 卖点卡片 */
.feature {
  background: #fff; border: 1px solid var(--line); border-radius: 24px;
  padding: 32px 30px; transition: transform .25s, box-shadow .25s, border-color .25s;
}
.feature:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: #ded9fb; }
.feature-ico {
  width: 46px; height: 46px; border-radius: 13px; display: flex; align-items: center; justify-content: center;
  background: linear-gradient(135deg, rgba(108, 59, 255, .12), rgba(59, 91, 255, .1)); margin-bottom: 20px;
}
.feature-ico svg { width: 23px; height: 23px; stroke: var(--brand); }
.feature h3 { font-size: 19px; margin-bottom: 10px; }
.feature p { font-size: 14.5px; color: var(--text-2); line-height: 1.8; }

/* 应用图标 */
.apps-head { text-align: center; }
.app-grid {
  display: grid; grid-template-columns: repeat(6, minmax(0, 1fr)); gap: 20px;
  margin: 48px auto 0; max-width: 860px;
}
.app-item {
  aspect-ratio: 1; border-radius: 18px; background: #fff; border: 1px solid var(--line);
  display: flex; align-items: center; justify-content: center; padding: 10px;
  transition: transform .25s, box-shadow .25s;
}
.app-item:hover { transform: translateY(-5px) scale(1.03); box-shadow: var(--shadow-lg); }
.app-item img {
  width: auto; height: 74%; max-width: 100%; object-fit: contain;
  image-rendering: -webkit-optimize-contrast;
}
.apps-note { text-align: center; margin-top: 34px; font-size: 15px; color: rgba(255, 255, 255, .6); }

/* 下载区 */
.download-grid { display: grid; grid-template-columns: 320px 1fr; gap: 56px; align-items: center; }
.qr-card {
  background: #fff; border-radius: 24px; padding: 26px; text-align: center; box-shadow: var(--shadow-lg);
}
.qr-card img { width: 100%; border-radius: 12px; }
.qr-card h3 { font-size: 18px; margin-top: 18px; }
.qr-card p { font-size: 13.5px; color: var(--text-3); margin-top: 6px; }
.dl-list { display: grid; grid-template-columns: repeat(2, 1fr); gap: 14px; }
.dl-item {
  display: flex; align-items: center; gap: 14px; padding: 18px 20px; border-radius: 14px;
  background: #fff; border: 1px solid var(--line); transition: border-color .2s, transform .2s, box-shadow .2s;
}
.dl-item:hover { border-color: #cbb8ff; transform: translateY(-2px); box-shadow: var(--shadow); }
.dl-ico { width: 40px; height: 40px; border-radius: 11px; display: flex; align-items: center; justify-content: center; background: var(--bg-soft); flex-shrink: 0; }
.dl-ico svg { width: 20px; height: 20px; fill: var(--text); }
.dl-item b { display: block; font-size: 15px; }
.dl-item span { font-size: 12.5px; color: var(--text-3); }

/* 博客卡片 */
.post {
  background: #fff; border: 1px solid var(--line); border-radius: 24px;
  overflow: hidden; display: flex; flex-direction: column; transition: transform .25s, box-shadow .25s, border-color .25s;
}
.post:hover { transform: translateY(-4px); box-shadow: var(--shadow-lg); border-color: #ded9fb; }
.post-cover { aspect-ratio: 16 / 9; overflow: hidden; background: var(--bg-soft); }
.post-cover img { width: 100%; height: 100%; object-fit: cover; transition: transform .5s; }
.post:hover .post-cover img { transform: scale(1.05); }
.post-body { padding: 20px 22px 24px; display: flex; flex-direction: column; flex: 1; }
.post-meta { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; margin-bottom: 12px; font-size: 12.5px; color: var(--text-3); }
.post-tag { padding: 2px 9px; border-radius: 6px; background: rgba(108, 59, 255, .08); color: var(--brand); font-weight: 600; }
.post h3 { font-size: 17.5px; line-height: 1.55; }
.post p { margin-top: 10px; font-size: 14px; color: var(--text-2); line-height: 1.8; flex: 1; }
.post-more { margin-top: 16px; font-size: 13.5px; color: var(--brand); font-weight: 600; }

/* FAQ */
.faq-list { max-width: 820px; margin: 0 auto; display: flex; flex-direction: column; gap: 12px; }
.faq-item { background: #fff; border: 1px solid var(--line); border-radius: 14px; overflow: hidden; }
.faq-item[open] { border-color: #d9cffd; box-shadow: var(--shadow); }
.faq-item summary {
  list-style: none; cursor: pointer; padding: 18px 52px 18px 22px; position: relative;
  font-size: 16px; font-weight: 600;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after {
  content: ""; position: absolute; right: 22px; top: 50%; width: 9px; height: 9px; margin-top: -6px;
  border-right: 2px solid var(--text-3); border-bottom: 2px solid var(--text-3);
  transform: rotate(45deg); transition: transform .22s;
}
.faq-item[open] summary::after { transform: rotate(-135deg); margin-top: -2px; }
.faq-body { padding: 0 22px 20px; font-size: 14.5px; color: var(--text-2); line-height: 1.85; }
.faq-body p { margin-bottom: 10px; }
.faq-body img { margin-top: 12px; border-radius: 10px; border: 1px solid var(--line); }

/* 协议 */
.legal-card { background: #fff; border: 1px solid var(--line); border-radius: 24px; padding: 30px 28px; }
.legal-card h3 { font-size: 19px; margin-bottom: 16px; display: flex; align-items: center; gap: 10px; }
.legal-card h3 i { width: 8px; height: 8px; border-radius: 50%; background: var(--brand); flex-shrink: 0; }
.legal-card li { position: relative; padding: 8px 0 8px 18px; font-size: 14.5px; color: var(--text-2); border-bottom: 1px dashed var(--line); }
.legal-card li:last-child { border-bottom: 0; }
.legal-card li::before { content: ""; position: absolute; left: 0; top: 17px; width: 6px; height: 6px; border-radius: 50%; background: #c4b5fd; }
.legal-card .note { margin-top: 14px; font-size: 13px; color: var(--text-3); line-height: 1.75; }

/* ============================ 页脚 ============================ */
.foot { background: var(--ink); color: rgba(255, 255, 255, .68); padding: 64px 0 28px; }
.foot-top { display: grid; grid-template-columns: 1.4fr repeat(3, 1fr); gap: 40px; padding-bottom: 40px; border-bottom: 1px solid rgba(255, 255, 255, .1); }
.foot-brand img {
  height: 34px; width: auto;
  image-rendering: -webkit-optimize-contrast;
}
.foot-brand p { margin-top: 16px; font-size: 13.5px; line-height: 1.8; max-width: 300px; }
.foot-social { display: flex; gap: 10px; margin-top: 20px; }
.foot-social a {
  width: 36px; height: 36px; border-radius: 10px; border: 1px solid rgba(255, 255, 255, .14);
  display: flex; align-items: center; justify-content: center;
}
.foot-social a:hover { background: rgba(255, 255, 255, .1); }
.foot-social svg { width: 17px; height: 17px; fill: currentColor; }
.foot-social svg.s-stroke { fill: none; stroke: currentColor; stroke-width: 1.9; }
.foot h4 { font-size: 14px; color: #fff; margin-bottom: 16px; }
.foot li { margin-bottom: 10px; }
.foot li a { font-size: 13.5px; }
.foot li a:hover { color: #fff; }
.foot-bottom { display: flex; flex-wrap: wrap; gap: 14px; justify-content: space-between; padding-top: 22px; font-size: 12.5px; color: rgba(255, 255, 255, .42); }

/* ============================ 登录弹窗 ============================ */
.modal { position: fixed; inset: 0; z-index: 200; display: flex; align-items: center; justify-content: center; padding: 20px; }
.modal[hidden] { display: none; }
.modal-mask { position: absolute; inset: 0; background: rgba(13, 13, 26, .58); backdrop-filter: blur(3px); }
.modal-box {
  position: relative; width: 400px; max-width: 100%; background: #fff; border-radius: 20px;
  padding: 34px 32px; box-shadow: 0 30px 70px rgba(10, 10, 30, .35);
  animation: pop .24s cubic-bezier(.16, 1, .3, 1);
}
@keyframes pop { from { opacity: 0; transform: translateY(14px) scale(.97); } to { opacity: 1; transform: none; } }
.modal-close { position: absolute; right: 16px; top: 12px; width: 32px; height: 32px; border: 0; background: transparent; color: var(--text-3); font-size: 24px; line-height: 1; border-radius: 8px; }
.modal-close:hover { background: var(--bg-soft); color: var(--text); }
.modal-box h2 { font-size: 22px; }
.modal-box > p { margin-top: 8px; font-size: 13.5px; color: var(--text-2); }
.field { position: relative; margin-top: 16px; }
.field input {
  width: 100%; height: 46px; padding: 0 14px 0 42px; border: 1px solid var(--line);
  border-radius: 11px; font-size: 14.5px; outline: none; background: #fff; color: var(--text);
}
.field input:focus { border-color: var(--brand); box-shadow: 0 0 0 3px rgba(108, 59, 255, .13); }
.field svg { position: absolute; left: 14px; top: 50%; margin-top: -9px; width: 18px; height: 18px; stroke: var(--text-3); fill: none; }
.field .toggle { position: absolute; right: 12px; top: 50%; margin-top: -9px; width: 18px; height: 18px; stroke: var(--text-3); fill: none; cursor: pointer; }
.form-msg { min-height: 22px; margin-top: 10px; font-size: 13px; color: #e5484d; }
.modal .btn-primary { width: 100%; margin-top: 8px; height: 46px; }
.modal-foot { margin-top: 16px; font-size: 12.5px; color: var(--text-3); text-align: center; }
.account-view { text-align: center; }
.account-view h3 { font-size: 20px; }
.account-view p { margin: 10px 0 20px; font-size: 14px; color: var(--text-2); }
.account-view .btn-ghost { width: 100%; }

/* ============================ 动效 ============================
   默认可见；仅当 JS 就绪并启用 IntersectionObserver 时才隐藏并播放入场动画，
   保证 JS 失败 / 被禁用时内容依然完整可读 */
.reveal { opacity: 1; transform: none; }
.has-reveal .reveal {
  opacity: 0; transform: translateY(26px);
  transition: opacity .7s cubic-bezier(.16, 1, .3, 1), transform .7s cubic-bezier(.16, 1, .3, 1);
}
.has-reveal .reveal.in { opacity: 1; transform: none; }

.to-top {
  position: fixed; right: 22px; bottom: 22px; z-index: 90; width: 44px; height: 44px; border-radius: 12px;
  background: #fff; border: 1px solid var(--line); box-shadow: var(--shadow);
  display: flex; align-items: center; justify-content: center; opacity: 0; pointer-events: none; transform: translateY(10px);
  transition: .25s;
}
.to-top.show { opacity: 1; pointer-events: auto; transform: none; }
.to-top:hover { border-color: #cbb8ff; color: var(--brand); }
.to-top svg { width: 18px; height: 18px; stroke: currentColor; fill: none; }

/* ============================ 响应式 ============================ */
@media screen and (max-width: 1024px) {
  .hero h1 { font-size: 44px; }
  .hero .wrap { grid-template-columns: 1fr; gap: 40px; }
  .hero-visual { order: -1; }
  .hero-visual img { max-width: 380px; }
  .app-grid { grid-template-columns: repeat(4, 1fr); }
  .download-grid { grid-template-columns: 1fr; gap: 34px; }
  .qr-card { max-width: 320px; margin: 0 auto; }
  .foot-top { grid-template-columns: 1fr 1fr; gap: 32px; }
}

@media screen and (max-width: 760px) {
  :root { --head-h: 58px; }
  .wrap { padding: 0 18px; }
  .section { padding: 64px 0; }
  .head-nav {
    position: fixed; inset: var(--head-h) 0 auto; flex-direction: column; align-items: stretch; gap: 2px;
    background: #fff; border-bottom: 1px solid var(--line); padding: 12px 18px 18px; margin-left: 0;
    box-shadow: var(--shadow-lg); display: none;
  }
  .head.nav-open .head-nav { display: flex; }
  .head-nav a { padding: 11px 12px; font-size: 15px; }
  .head-actions { margin-left: auto; }
  .burger { display: flex; }
  .head-actions .btn-ghost { display: none; }
  .hero { padding: calc(var(--head-h) + 52px) 0 64px; }
  .hero h1 { font-size: 32px; }
  .hero-sub { font-size: 15px; margin-top: 16px; }
  .hero-cta { margin-top: 26px; gap: 10px; }
  .hero-cta .btn { flex: 1 1 auto; }
  .btn-lg { padding: 12px 20px; font-size: 15px; }
  .hero-metrics { gap: 0; justify-content: space-between; margin-top: 32px; padding-top: 22px; }
  .hero-metrics div b { font-size: 25px; }
  .hero-metrics div span { font-size: 12px; }
  .sec-head { margin-bottom: 34px; }
  .sec-head h2 { font-size: 26px; }
  .sec-head p { font-size: 14.5px; margin-top: 12px; }
  .grid { gap: 16px; }
  .grid-3, .grid-2 { grid-template-columns: 1fr; }
  .feature { padding: 24px 22px; }
  .app-grid { grid-template-columns: repeat(4, 1fr); gap: 12px; margin-top: 32px; }
  .app-item { border-radius: 14px; }
  .dl-list { grid-template-columns: 1fr; }
  .faq-item summary { font-size: 15px; padding: 15px 44px 15px 18px; }
  .faq-body { padding: 0 18px 16px; font-size: 14px; }
  .legal-card { padding: 24px 20px; }
  .foot { padding: 48px 0 24px; }
  .foot-top { grid-template-columns: 1fr; gap: 26px; }
  .modal-box { padding: 28px 22px; }
  .to-top { right: 14px; bottom: 14px; }
}

@media screen and (max-width: 420px) {
  .app-grid { grid-template-columns: repeat(3, 1fr); }
  .hero-eyebrow { font-size: 12px; gap: 10px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal, .has-reveal .reveal { opacity: 1; transform: none; transition: none; }
  * { animation-duration: .01ms !important; transition-duration: .01ms !important; }
}