:root {
  --bg: #F4F5F7;
  --surface: #FFFFFF;
  --ink: #0B0C0F;
  --ink-2: #4B5160;
  --ink-3: #8A90A0;
  --line: rgba(11, 12, 15, 0.09);
  --line-strong: rgba(11, 12, 15, 0.16);
  --radius: 14px;
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Text", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  color-scheme: light;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.7 var(--font);
  -webkit-font-smoothing: antialiased;
}
a { color: inherit; text-decoration-color: var(--line-strong); text-underline-offset: 3px; }
a:hover { text-decoration-color: var(--ink); }

.wrap { max-width: 1040px; margin: 0 auto; padding: 0 24px; }

/* 顶栏 */
.nav { display: flex; align-items: center; justify-content: space-between; height: 72px; }
.brand { display: inline-flex; align-items: center; gap: 10px; text-decoration: none;
  font-weight: 600; font-size: 19px; letter-spacing: -0.025em; white-space: nowrap; }
.brand svg { width: 28px; height: 28px; display: block; }
.nav-links { display: flex; align-items: center; gap: 28px; font-size: 14px; color: var(--ink-2); }
.nav-links a { text-decoration: none; white-space: nowrap; }
.nav-links a:hover, .nav-links a[aria-current] { color: var(--ink); }
.nav-links .nav-cta { color: #fff; background: var(--ink); padding: 7px 14px; border-radius: 999px; }
.nav-links .nav-cta:hover { color: #fff; opacity: .85; }

/* 首屏 */
.hero { display: grid; grid-template-columns: 1.15fr 0.85fr; gap: 56px; align-items: center;
  padding: 72px 0 96px; }
.eyebrow { font-size: 13px; color: var(--ink-3); letter-spacing: 0.06em; margin: 0 0 20px; }
h1 { font-size: 52px; line-height: 1.16; letter-spacing: -0.035em; font-weight: 650; margin: 0 0 24px; }
.lede { font-size: 18px; line-height: 1.75; color: var(--ink-2); margin: 0 0 36px; max-width: 30em; }
.cta { display: flex; flex-wrap: wrap; gap: 14px; align-items: center; }
.pill { display: inline-flex; align-items: center; height: 44px; padding: 0 22px; border-radius: 999px;
  background: var(--ink); color: #fff; font-size: 15px; font-weight: 500; }
.pill.ghost { background: transparent; color: var(--ink); border: 1px solid var(--line-strong);
  text-decoration: none; }
.pill.ghost:hover { border-color: var(--ink); }

/* 首屏右侧：回复面板示意 */
.panel { background: var(--surface); border: 1px solid var(--line); border-radius: 22px;
  padding: 18px; box-shadow: 0 1px 0 rgba(11,12,15,.03), 0 24px 48px -24px rgba(11,12,15,.18); }
.panel .tag { font-size: 12px; color: var(--ink-3); margin: 0 4px 12px; display: flex;
  justify-content: space-between; }
.msg { background: var(--bg); border-radius: 12px; padding: 12px 14px; font-size: 14px; line-height: 1.6;
  color: var(--ink-2); margin-bottom: 14px; }
.msg b { display: block; font-size: 12px; font-weight: 500; color: var(--ink-3); margin-bottom: 2px; }
.reply { border: 1px solid var(--line); border-radius: 12px; padding: 12px 14px; font-size: 14px;
  line-height: 1.6; margin-top: 8px; }
.reply.pick { border-color: var(--ink); }

/* 功能 */
section { padding: 0 0 96px; }
.sec-title { font-size: 30px; letter-spacing: -0.025em; line-height: 1.3; font-weight: 650; margin: 0 0 12px; }
.sec-sub { color: var(--ink-2); margin: 0 0 40px; max-width: 34em; }
.grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; }
.card { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 26px 24px 28px; }
.card h3 { font-size: 17px; letter-spacing: -0.01em; margin: 18px 0 8px; font-weight: 600; }
.card p { margin: 0; font-size: 14.5px; line-height: 1.75; color: var(--ink-2); }
.ico { width: 36px; height: 36px; border-radius: 10px; background: var(--bg); display: grid; place-items: center; }
.ico svg { width: 20px; height: 20px; stroke: var(--ink); fill: none; stroke-width: 1.6;
  stroke-linecap: round; stroke-linejoin: round; }

/* 隐私带 */
.band { background: var(--ink); color: #F5F6F8; border-radius: 22px; padding: 56px 48px; }
.band .sec-title { color: #fff; }
.band .sec-sub { color: rgba(245,246,248,.66); margin-bottom: 36px; }
.band ul { list-style: none; padding: 0; margin: 0 0 32px; display: grid;
  grid-template-columns: repeat(3, 1fr); gap: 28px; }
.band li { border-top: 1px solid rgba(255,255,255,.16); padding-top: 18px; font-size: 15px;
  line-height: 1.7; color: rgba(245,246,248,.86); }
.band li b { display: block; color: #fff; font-weight: 600; margin-bottom: 4px; font-size: 16px; }
.band a { color: #fff; font-size: 15px; }

/* 页脚 */
footer { border-top: 1px solid var(--line); padding: 32px 0 48px; font-size: 13px; color: var(--ink-3);
  margin-top: 24px; }
footer .wrap { display: flex; flex-wrap: wrap; gap: 8px 28px; justify-content: space-between; }
footer a { text-decoration: none; }
footer a:hover { color: var(--ink); }
footer .links { display: flex; gap: 20px; flex-wrap: wrap; }

/* 文档页（隐私、支持） */
.doc { max-width: 760px; margin: 0 auto; padding: 40px 0 96px; }
.doc h1 { font-size: 38px; margin-bottom: 20px; }
.doc h2 { font-size: 22px; letter-spacing: -0.02em; margin: 48px 0 12px; font-weight: 650; }
.doc h3 { font-size: 17px; margin: 30px 0 8px; font-weight: 600; }
.doc p, .doc li { color: #2A2E38; font-size: 15.5px; line-height: 1.85; }
.doc p { margin: 0 0 14px; }
.doc ul, .doc ol { padding-left: 1.4em; margin: 0 0 14px; }
.doc li { margin-bottom: 6px; }
.doc hr { border: 0; border-top: 1px solid var(--line); margin: 40px 0 0; }
.doc strong { color: var(--ink); font-weight: 600; }
.table-scroll { overflow-x: auto; margin: 0 0 18px; }
.doc table { border-collapse: collapse; width: 100%; font-size: 14.5px; min-width: 480px;
  background: var(--surface); border: 1px solid var(--line); border-radius: 10px; }
.doc th, .doc td { text-align: left; padding: 10px 14px; border-bottom: 1px solid var(--line);
  vertical-align: top; line-height: 1.7; }
.doc th { font-weight: 600; background: #FAFAFB; white-space: nowrap; }
.doc tr:last-child td { border-bottom: 0; }
.pending { background: #FFF1B8; padding: 0 4px; border-radius: 4px; }

.faq { border-top: 1px solid var(--line); }
.faq details { border-bottom: 1px solid var(--line); padding: 18px 0; }
.faq summary { cursor: pointer; font-weight: 600; font-size: 16px; list-style: none; display: flex;
  justify-content: space-between; gap: 16px; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; color: var(--ink-3); font-weight: 400; font-size: 20px; line-height: 1.3; }
.faq details[open] summary::after { content: "–"; }
.faq details p, .faq details ol { margin: 12px 0 0; }
.contact { background: var(--surface); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 22px 24px; margin: 28px 0 48px; }
.contact p { margin: 0; }
.contact .mail { font-size: 20px; font-weight: 600; letter-spacing: -0.01em; }

@media (max-width: 860px) {
  .hero { grid-template-columns: 1fr; gap: 40px; padding: 40px 0 64px; }
  h1 { font-size: 38px; }
  .grid { grid-template-columns: 1fr 1fr; }
  .band { padding: 40px 28px; }
  .band ul { grid-template-columns: 1fr; gap: 20px; }
  section { padding-bottom: 64px; }
}
@media (max-width: 560px) {
  .wrap { padding: 0 16px; }
  .grid { grid-template-columns: 1fr; }
  h1 { font-size: 32px; }
  .lede { font-size: 16.5px; }
  .nav-links { gap: 18px; }
  /* 窄屏顶栏只留「登录」：隐私政策和技术支持页脚里都有，挤在一行会把品牌名折断 */
  .nav-links a:not(.nav-cta) { display: none; }
  .doc h1 { font-size: 30px; }
}