/* chat 官方下载页。CSP 只允许同源样式：不要写内联 style，也不要引用外部字体。 */

:root {
  color-scheme: light;
  --bg: #ffffff;
  --bg-soft: #f5f7fc;
  --surface: #ffffff;
  --surface-2: #eef2f8;
  --ink: #0f172a;
  --ink-2: #334155;
  --muted: #5b6678;
  --line: #e3e8f1;
  --brand: #2f6feb;
  --brand-hover: #2560d6;
  --brand-ink: #1f56c9;
  --brand-soft: #e9f0ff;
  --glow-1: #dce8ff;
  --glow-2: #efe8ff;
  --shadow: 0 1px 2px rgb(15 23 42 / .04), 0 16px 40px -20px rgb(15 23 42 / .18);
  --phone-frame: #111827;
  --screen: #fbfcff;
  --bubble-me: #d9e4ff;
  --bubble-me-ink: #0c1f4f;
  --bubble-peer: #edf0f6;
  --header-bg: rgb(255 255 255 / .82);
  --radius: 20px;
}

@media (prefers-color-scheme: dark) {
  :root {
    color-scheme: dark;
    --bg: #0b0f19;
    --bg-soft: #0f1524;
    --surface: #131a2b;
    --surface-2: #1a2236;
    --ink: #eef2f9;
    --ink-2: #c8d1e1;
    --muted: #97a3b8;
    --line: #232c42;
    --brand-ink: #8db0ff;
    --brand-soft: #18264a;
    --glow-1: rgb(47 111 235 / .26);
    --glow-2: rgb(124 92 255 / .14);
    --shadow: 0 1px 2px rgb(0 0 0 / .3), 0 16px 40px -20px rgb(0 0 0 / .7);
    --phone-frame: #02040a;
    --screen: #0f1626;
    --bubble-me: #284a99;
    --bubble-me-ink: #eef3ff;
    --bubble-peer: #1d2638;
    --header-bg: rgb(11 15 25 / .8);
  }
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: system-ui, -apple-system, "PingFang SC", "HarmonyOS Sans SC", "MiSans", "Noto Sans SC", "Noto Sans CJK SC", "Microsoft YaHei", sans-serif;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

img, svg { display: block; }
a { color: var(--brand-ink); }
h1, h2, h3, p { margin: 0; }
ul, ol { margin: 0; padding: 0; list-style: none; }

a:focus-visible, summary:focus-visible {
  outline: 3px solid var(--brand);
  outline-offset: 4px;
  border-radius: 6px;
}

.sprite { position: absolute; width: 0; height: 0; overflow: hidden; }
.icon { width: 24px; height: 24px; fill: currentColor; flex: none; }

.skip {
  position: absolute; left: 16px; top: -80px; z-index: 20;
  padding: 10px 16px; border-radius: 10px;
  background: var(--surface); color: var(--ink); box-shadow: var(--shadow);
}
.skip:focus { top: 12px; }

.wrap { width: 100%; max-width: 1140px; margin: 0 auto; padding: 0 28px; }
.wrap.narrow { max-width: 820px; }

/* 顶栏 */
.site-header {
  position: sticky; top: 0; z-index: 10;
  background: var(--header-bg);
  -webkit-backdrop-filter: saturate(1.6) blur(14px);
  backdrop-filter: saturate(1.6) blur(14px);
  border-bottom: 1px solid transparent;
}
.header-inner { display: flex; align-items: center; gap: 32px; height: 64px; }
.brand {
  display: inline-flex; align-items: center; gap: 10px;
  color: var(--ink); text-decoration: none; font-weight: 750; font-size: 19px; letter-spacing: -.01em;
}
.brand img { border-radius: 9px; }
.nav { display: flex; gap: 28px; margin-left: auto; }
.nav a { color: var(--ink-2); text-decoration: none; font-size: 15px; }
.nav a:hover { color: var(--ink); }
.header-download {
  display: inline-flex; align-items: center; height: 38px; padding: 0 18px; border-radius: 999px;
  background: var(--ink); color: var(--bg); text-decoration: none; font-size: 14px; font-weight: 650;
  transition: opacity .18s;
}
.header-download:hover { opacity: .86; }

/* 首屏 */
.hero {
  position: relative; overflow: hidden;
  background:
    radial-gradient(48% 56% at 82% 30%, var(--glow-1), transparent 70%),
    radial-gradient(40% 46% at 8% 0%, var(--glow-2), transparent 72%),
    var(--bg);
}
.hero-inner {
  display: grid; grid-template-columns: 1.1fr .9fr; align-items: center; gap: 48px;
  padding-top: 72px; padding-bottom: 88px;
}
.pill {
  display: inline-flex; align-items: center; gap: 10px;
  padding: 5px 14px 5px 5px; border-radius: 999px;
  background: var(--surface); border: 1px solid var(--line);
  color: var(--ink-2); font-size: 14px;
}
.pill span {
  padding: 2px 10px; border-radius: 999px;
  background: var(--brand-soft); color: var(--brand-ink); font-weight: 700; font-size: 13px;
}
h1 {
  margin-top: 24px;
  font-size: clamp(40px, 5.6vw, 66px); line-height: 1.12; font-weight: 800; letter-spacing: -.02em;
}
.lead { margin-top: 22px; max-width: 34em; color: var(--muted); font-size: 18px; }
.actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 34px; }
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 10px;
  min-height: 54px; padding: 0 26px; border-radius: 16px;
  font-size: 17px; font-weight: 650; text-decoration: none;
  transition: background .18s, transform .18s, box-shadow .18s, border-color .18s;
}
.btn-primary { background: var(--brand); color: #fff; box-shadow: 0 10px 24px -10px rgb(47 111 235 / .7); }
.btn-primary:hover { background: var(--brand-hover); transform: translateY(-1px); }
.btn-ghost { color: var(--ink); border: 1px solid var(--line); background: var(--surface); }
.btn-ghost:hover { border-color: var(--muted); }
.meta {
  display: flex; flex-wrap: wrap; gap: 6px 20px; margin-top: 22px;
  color: var(--muted); font-size: 14px;
}
.meta span { display: inline-flex; align-items: center; gap: 6px; }
.meta .icon { width: 18px; height: 18px; color: #3ddc84; }

/* 手机示意图：比例、圆角和气泡样式参照 App 的 Material 3 界面 */
.hero-visual { display: flex; justify-content: center; }
.phone {
  width: min(300px, 100%); aspect-ratio: 300 / 620; padding: 10px; border-radius: 46px;
  background: var(--phone-frame);
  box-shadow: 0 0 0 1px rgb(255 255 255 / .08) inset, 0 50px 90px -40px rgb(31 86 201 / .55), 0 24px 40px -24px rgb(15 23 42 / .4);
  animation: rise .8s cubic-bezier(.2, .7, .2, 1) both;
}
.screen {
  height: 100%; border-radius: 37px; overflow: hidden;
  display: flex; flex-direction: column;
  background: var(--screen); color: var(--ink); font-size: 13px; line-height: 1.45;
}
.statusbar {
  position: relative; display: flex; align-items: center; justify-content: space-between;
  height: 34px; padding: 0 24px; font-size: 12px; font-weight: 650;
}
.cam { position: absolute; left: 50%; top: 11px; width: 11px; height: 11px; margin-left: -5.5px; border-radius: 50%; background: #05070d; }
.battery { width: 20px; height: 10px; border-radius: 3px; border: 1.5px solid currentColor; opacity: .75; position: relative; }
.battery::after { content: ""; position: absolute; inset: 1.5px 5px 1.5px 1.5px; border-radius: 1px; background: currentColor; }
.appbar {
  display: flex; align-items: center; gap: 10px;
  padding: 6px 14px 10px; border-bottom: 1px solid var(--line);
}
.appbar .icon { width: 20px; height: 20px; color: var(--ink-2); }
.avatar {
  display: grid; place-items: center; width: 30px; height: 30px; border-radius: 50%;
  background: var(--brand-soft); color: var(--brand-ink); font-size: 13px; font-weight: 700;
}
.peer-name { font-size: 15px; font-weight: 650; }
.thread {
  flex: 1; min-height: 0; overflow: hidden;
  display: flex; flex-direction: column; justify-content: flex-end; gap: 8px;
  padding: 12px;
}
.notice {
  align-self: center; padding: 3px 10px; border-radius: 999px;
  background: var(--surface-2); color: var(--muted); font-size: 10.5px;
}
.msg { max-width: 80%; padding: 8px 12px 5px; border-radius: 18px; }
.msg time { display: block; margin-top: 1px; text-align: right; font-size: 9.5px; opacity: .6; }
.peer { align-self: flex-start; background: var(--bubble-peer); border-bottom-left-radius: 6px; }
.me { align-self: flex-end; background: var(--bubble-me); color: var(--bubble-me-ink); border-bottom-right-radius: 6px; }
.photo-msg { padding: 6px 6px 4px; }
.photo-msg time { padding-right: 6px; }
.photo {
  position: relative; overflow: hidden; width: 170px; height: 112px; border-radius: 12px;
  background: linear-gradient(180deg, #7ea6ff 0%, #b9c9ff 45%, #ffd2a8 100%);
}
.photo i { position: absolute; display: block; }
.sun { right: 30px; top: 22px; width: 26px; height: 26px; border-radius: 50%; background: #fff4d6; box-shadow: 0 0 24px 8px rgb(255 240 200 / .7); }
.ridge.far { left: -10%; right: -10%; bottom: 0; height: 70%; background: #6d86c9; clip-path: polygon(0 100%, 0 60%, 22% 30%, 38% 52%, 58% 12%, 78% 46%, 100% 28%, 100% 100%); }
.ridge.near { left: -10%; right: -10%; bottom: 0; height: 48%; background: #34518f; clip-path: polygon(0 100%, 0 52%, 18% 30%, 36% 62%, 54% 36%, 72% 70%, 90% 40%, 100% 54%, 100% 100%); }
.voice { display: flex; align-items: center; gap: 9px; padding: 7px 12px 7px 7px; }
.play { display: grid; place-items: center; width: 28px; height: 28px; border-radius: 50%; background: var(--brand); color: #fff; }
.play .icon { width: 18px; height: 18px; }
.wave { display: flex; align-items: center; gap: 2.5px; height: 22px; }
.wave i { width: 3px; height: 8px; border-radius: 2px; background: currentColor; opacity: .5; }
.wave i:nth-child(2), .wave i:nth-child(9) { height: 14px; }
.wave i:nth-child(3), .wave i:nth-child(7) { height: 20px; }
.wave i:nth-child(4), .wave i:nth-child(11) { height: 11px; }
.wave i:nth-child(5) { height: 16px; }
.wave i:nth-child(6), .wave i:nth-child(10) { height: 6px; }
.secs { font-weight: 650; font-size: 13px; }
.sent { align-self: flex-end; margin-top: -4px; padding-right: 4px; color: var(--muted); font-size: 10px; }
.composer {
  display: flex; align-items: center; gap: 12px;
  padding: 10px 14px 16px; border-top: 1px solid var(--line); color: var(--ink-2);
}
.composer .icon { width: 21px; height: 21px; }
.field {
  flex: 1; display: flex; align-items: center; height: 36px; padding: 0 14px; border-radius: 18px;
  background: var(--surface-2); color: var(--muted); font-size: 12.5px;
}
.thread > * { animation: pop .5s cubic-bezier(.2, .7, .2, 1) both; }
.thread > :nth-child(2) { animation-delay: .35s; }
.thread > :nth-child(3) { animation-delay: .6s; }
.thread > :nth-child(4) { animation-delay: .85s; }
.thread > :nth-child(5) { animation-delay: 1.1s; }
.thread > :nth-child(6) { animation-delay: 1.35s; }
.thread > :nth-child(7) { animation-delay: 1.5s; }

/* 通用区块 */
.section { padding: 104px 0; scroll-margin-top: 64px; }
.section-soft { background: var(--bg-soft); }
.section-head { max-width: 640px; margin-bottom: 48px; }
.eyebrow { color: var(--brand-ink); font-size: 14px; font-weight: 700; letter-spacing: .08em; }
h2 { margin-top: 10px; font-size: clamp(28px, 3.4vw, 40px); line-height: 1.25; font-weight: 800; letter-spacing: -.015em; }
.section-lead { margin-top: 14px; color: var(--muted); font-size: 17px; }
h3 { font-size: 18px; line-height: 1.4; font-weight: 700; }

/* 功能 */
.features { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.card {
  padding: 28px; border-radius: var(--radius);
  background: var(--surface); border: 1px solid var(--line);
  transition: transform .2s, box-shadow .2s;
}
.card:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.card-icon {
  display: grid; place-items: center; width: 48px; height: 48px; margin-bottom: 20px; border-radius: 14px;
  background: var(--brand-soft); color: var(--brand-ink);
}
.card p { margin-top: 8px; color: var(--muted); font-size: 15px; }
.chips { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 28px; }
.chips li {
  padding: 6px 14px; border-radius: 999px; border: 1px solid var(--line);
  color: var(--ink-2); font-size: 14px;
}

/* 说在前面 */
.honest { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; }
.panel { padding: 32px; border-radius: var(--radius); background: var(--surface); border: 1px solid var(--line); }
.panel h3 { display: flex; align-items: center; gap: 10px; margin-bottom: 18px; }
.panel h3 .icon { color: var(--brand-ink); }
.list li { position: relative; padding-left: 20px; color: var(--ink-2); font-size: 15px; }
.list li + li { margin-top: 12px; }
.list li::before {
  content: ""; position: absolute; left: 2px; top: .7em;
  width: 6px; height: 6px; border-radius: 50%; background: var(--brand);
}
.list b { color: var(--ink); font-weight: 650; }

/* 接下来 */
.roadmap { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.roadmap li { padding: 26px; border-radius: var(--radius); border: 1px dashed var(--line); }
.roadmap .icon { width: 28px; height: 28px; margin-bottom: 16px; color: var(--brand-ink); }
.roadmap p { margin-top: 6px; color: var(--muted); font-size: 15px; }

/* 安装 */
.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; counter-reset: none; }
.steps li { padding: 28px; border-radius: var(--radius); background: var(--surface); border: 1px solid var(--line); }
.step-no {
  display: grid; place-items: center; width: 36px; height: 36px; margin-bottom: 18px; border-radius: 50%;
  background: var(--brand); color: #fff; font-weight: 750; font-size: 16px;
}
.steps p { margin-top: 8px; color: var(--muted); font-size: 15px; }

/* 常见问题 */
.faq { border-top: 1px solid var(--line); }
.faq details { border-bottom: 1px solid var(--line); }
.faq summary {
  display: flex; align-items: center; justify-content: space-between; gap: 24px;
  min-height: 64px; padding: 16px 0; cursor: pointer; list-style: none;
  font-size: 17px; font-weight: 650;
}
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after {
  content: "+"; flex: none; font-size: 24px; font-weight: 400; line-height: 1; color: var(--muted);
  transition: transform .2s;
}
.faq details[open] summary::after { transform: rotate(45deg); }
.faq p { padding-bottom: 22px; color: var(--muted); font-size: 15px; }
.checksum {
  display: block; margin: -8px 0 24px; padding: 12px 14px; border-radius: 12px;
  background: var(--surface-2); color: var(--ink-2); font-size: 13px; overflow-wrap: anywhere;
}

/* 底部下载 */
.cta { padding: 0 0 104px; }
.cta-card {
  display: flex; flex-direction: column; align-items: center; text-align: center;
  padding: 64px 28px; border-radius: 32px; color: #fff;
  background:
    radial-gradient(60% 80% at 85% 0%, rgb(255 255 255 / .16), transparent 70%),
    linear-gradient(135deg, #1d4fc4 0%, #2f6feb 100%);
}
.cta-card img { border-radius: 16px; box-shadow: 0 10px 30px -10px rgb(0 0 0 / .4); }
.cta-card h2 { margin-top: 24px; }
.cta-card > p { margin-top: 12px; font-size: 17px; opacity: .9; }
.btn-light { margin-top: 30px; background: #fff; color: #1d4fc4; }
.btn-light:hover { transform: translateY(-1px); box-shadow: 0 12px 28px -12px rgb(0 0 0 / .5); }
.cta-card .cta-meta { margin-top: 16px; font-size: 14px; opacity: .8; }

/* 页脚 */
.site-footer { border-top: 1px solid var(--line); }
.footer-inner {
  display: flex; flex-wrap: wrap; align-items: center; gap: 8px 28px;
  padding-top: 28px; padding-bottom: 36px; color: var(--muted); font-size: 13px;
}
.brand.small { font-size: 15px; gap: 8px; }
.brand.small img { border-radius: 6px; }
.footer-inner span:last-child { margin-left: auto; }

@keyframes rise { from { opacity: 0; transform: translateY(24px); } to { opacity: 1; transform: none; } }
@keyframes pop { from { opacity: 0; transform: translateY(10px) scale(.98); } to { opacity: 1; transform: none; } }

@media (max-width: 1020px) {
  .roadmap { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 900px) {
  .hero-inner { grid-template-columns: 1fr; gap: 56px; padding-top: 48px; padding-bottom: 72px; text-align: center; }
  .lead { margin-left: auto; margin-right: auto; }
  .actions, .meta { justify-content: center; }
  .features, .steps { grid-template-columns: repeat(2, 1fr); }
  .honest { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  .wrap { padding: 0 20px; }
  .nav { display: none; }
  .header-inner { justify-content: space-between; height: 58px; }
  .section { padding: 72px 0; scroll-margin-top: 58px; }
  .section-head { margin-bottom: 32px; }
  .hero-inner { padding-top: 36px; }
  h1 { margin-top: 20px; }
  .lead { font-size: 16px; }
  .actions { flex-direction: column; align-items: stretch; }
  .btn { width: 100%; }
  .meta { gap: 4px 14px; font-size: 13px; }
  .phone { width: min(276px, 100%); }
  .features, .steps, .roadmap { grid-template-columns: 1fr; gap: 14px; }
  .card, .steps li, .panel, .roadmap li { padding: 24px; }
  .faq summary { font-size: 16px; }
  .cta { padding-bottom: 72px; }
  .cta-card { padding: 48px 22px; border-radius: 26px; }
  .footer-inner { flex-direction: column; align-items: flex-start; }
  .footer-inner span:last-child { margin-left: 0; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
}