:root {
  --cloud: #f2f4f6;
  --paper: #ffffff;
  --ink: #14202b;
  --muted: #56636e;
  --ocean: #1d4f86;
  --rule: #d8dee4;
  --serif: "Noto Serif SC", "Songti SC", serif;
  --sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --cloud: #0f1820;
    --paper: #16212b;
    --ink: #e8edf1;
    --muted: #9aa8b3;
    --ocean: #7fb0e6;
    --rule: #26333f;
  }
}

* { box-sizing: border-box; }

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

body {
  margin: 0;
  background: var(--cloud);
  color: var(--ink);
  font: 17px/1.75 var(--sans);
}

a { color: var(--ocean); text-underline-offset: 3px; }
a:focus-visible { outline: 2px solid var(--ocean); outline-offset: 3px; border-radius: 2px; }

img { display: block; max-width: 100%; height: auto; }

.wrap { width: min(1080px, 100% - 32px); margin-inline: auto; }

/* 首屏：整屏照片，标题压在照片上 */
.hero {
  position: relative;
  min-height: min(92vh, 860px);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  color: #fff;
  background: #0a1622 url("images/hero-earth.jpg") center 35% / cover no-repeat;
}

.hero::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(to bottom, rgba(5, 12, 20, .55) 0%, rgba(5, 12, 20, 0) 30%, rgba(5, 12, 20, 0) 45%, rgba(5, 12, 20, .72) 100%);
}

.hero > * { position: relative; z-index: 1; }

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  padding-top: 24px;
  color: inherit;
  text-decoration: none;
  font-weight: 600;
  letter-spacing: .04em;
}

.brand img { width: 36px; height: 36px; border-radius: 9px; }

.hero-copy { padding-bottom: 56px; }

.hero h1 {
  margin: 0;
  font: 700 clamp(48px, 9vw, 112px)/1.08 var(--serif);
  letter-spacing: .02em;
}

.hero p {
  max-width: 30em;
  margin: 20px 0 0;
  font-size: clamp(17px, 2vw, 20px);
  color: rgba(255, 255, 255, .88);
}

.status {
  display: inline-block;
  margin-top: 28px;
  padding: 10px 18px;
  border: 1px solid rgba(255, 255, 255, .55);
  border-radius: 999px;
  font-size: 15px;
}

.credit {
  position: absolute;
  right: 16px;
  bottom: 12px;
  z-index: 1;
  font-size: 12px;
  color: rgba(255, 255, 255, .6);
}

/* 图片来源：截图 + 列表 */
.sources {
  display: grid;
  grid-template-columns: minmax(0, 5fr) minmax(0, 6fr);
  gap: 64px;
  align-items: center;
  padding-block: 96px;
}

/* 两张截图错开摆放；高度跟宽度等比，窄屏也不会溢出 */
.phones { position: relative; aspect-ratio: 1 / 1.3; max-width: 480px; }

.phones img {
  position: absolute;
  width: 54%;
  border-radius: 7% / 3.2%;
  box-shadow: 0 30px 60px -30px rgba(10, 30, 50, .55);
}

.phones img:first-child { left: 0; top: 0; }
.phones img:last-child { right: 0; top: 9%; }

h2 {
  margin: 0 0 24px;
  font: 700 clamp(28px, 4vw, 40px)/1.3 var(--serif);
}

.source-list { margin: 0; padding: 0; list-style: none; }

.source-list li {
  padding: 18px 0;
  border-top: 1px solid var(--rule);
}

.source-list li:last-child { border-bottom: 1px solid var(--rule); }

.source-list strong {
  display: block;
  font: 600 20px/1.5 var(--serif);
}

.source-list span { color: var(--muted); }

/* 功能 */
.features {
  padding-block: 88px;
  background: var(--paper);
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 40px 64px;
  margin: 0;
}

.feature-grid dt { font: 600 20px/1.5 var(--serif); }
.feature-grid dd { margin: 6px 0 0; color: var(--muted); }

/* 页脚 */
footer {
  padding-block: 40px 48px;
  font-size: 15px;
  color: var(--muted);
}

footer .wrap {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 12px 32px;
}

footer nav { display: flex; flex-wrap: wrap; gap: 8px 24px; }

/* 隐私政策 */
.doc-header {
  padding-block: 24px;
  border-bottom: 1px solid var(--rule);
  background: var(--paper);
}

.doc-header .brand { padding: 0; color: var(--ink); }

.doc {
  width: min(720px, 100% - 32px);
  margin: 56px auto 80px;
}

.doc h1 { margin: 0 0 8px; font: 700 clamp(32px, 5vw, 44px)/1.3 var(--serif); }
.doc h2 { margin: 48px 0 12px; font-size: 24px; }
.doc .updated { margin: 0 0 32px; color: var(--muted); }
.doc .lang { margin-top: 72px; padding-top: 32px; border-top: 1px solid var(--rule); }
.doc ul { padding-left: 1.2em; }
.doc li + li { margin-top: 6px; }

@media (max-width: 760px) {
  .sources { grid-template-columns: 1fr; gap: 48px; padding-block: 64px; }
  .phones { margin-inline: auto; width: 100%; }
  .feature-grid { grid-template-columns: 1fr; gap: 28px; }
  .features { padding-block: 64px; }
  .hero-copy { padding-bottom: 48px; }
}