/* Bifrost 官网 · 2026-10-26 改版：连接中国与世界。浅色、克制，彩虹色只用在“桥”上。 */
:root {
  --ink: #0d1222;
  --ink-2: #3a4359;
  --muted: #5a637a;
  --line: #e4e7ef;
  --line-2: #eef0f5;
  --bg: #ffffff;
  --bg-soft: #f6f7fb;
  --accent: #2a5bf6;
  --accent-ink: #1d47d1;
  --accent-soft: #edf2ff;
  --dark: #0d1222;
  --rainbow: linear-gradient(90deg, #ff5a5f, #ffb347 25%, #3ccf8e 50%, #3d8bff 75%, #8b5cf6);
  --radius: 18px;
  --radius-sm: 12px;
  --shadow: 0 1px 2px rgba(13, 18, 34, .04), 0 8px 28px rgba(13, 18, 34, .06);
  --font: -apple-system, BlinkMacSystemFont, "SF Pro Text", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", "Segoe UI", Roboto, sans-serif;
}
html:lang(zh-Hant) { --font: -apple-system, BlinkMacSystemFont, "SF Pro Text", "PingFang TC", "Microsoft JhengHei", "Noto Sans TC", "Segoe UI", Roboto, sans-serif; }

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; scroll-padding-top: 80px; }
body { margin: 0; background: var(--bg); color: var(--ink); font: 16px/1.7 var(--font); -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility; overflow-x: hidden; }
h1, h2, h3 { text-wrap: balance; margin: 0; line-height: 1.25; letter-spacing: -.01em; font-weight: 700; }
p { margin: 0; }
a { color: var(--accent); text-decoration: none; }
a:hover { color: var(--accent-ink); text-decoration: underline; text-underline-offset: 3px; }
img, svg { display: block; max-width: 100%; }
:focus-visible { outline: 2.5px solid var(--accent); outline-offset: 3px; border-radius: 6px; }

.wrap { width: min(1120px, 100% - 32px); margin-inline: auto; }
.narrow { width: min(780px, 100% - 32px); }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.skip { position: absolute; left: 12px; top: -48px; z-index: 50; padding: 8px 14px; background: var(--ink); color: #fff; border-radius: 8px; }
.skip:focus { top: 12px; }
section > .wrap > h2, section > .narrow > h2 { font-size: clamp(26px, 3.4vw, 36px); }
.sub { margin-top: 10px; color: var(--muted); font-size: 17px; max-width: 46em; }
.more { margin-top: 24px; font-weight: 600; }

/* ---------- 顶栏 */
.topbar { position: sticky; top: 0; z-index: 20; background: rgba(255, 255, 255, .86); backdrop-filter: saturate(1.6) blur(14px); -webkit-backdrop-filter: saturate(1.6) blur(14px); border-bottom: 1px solid var(--line-2); }
.topbar-in { display: flex; align-items: center; gap: 20px; height: 64px; }
.brand { display: inline-flex; align-items: center; gap: 10px; color: var(--ink); font-weight: 750; font-size: 19px; letter-spacing: -.01em; }
.brand:hover { color: var(--ink); text-decoration: none; }
.brand img { width: 32px; height: 32px; border-radius: 9px; }
.nav { display: flex; align-items: center; gap: 4px; margin-left: auto; }
.nav > a { padding: 8px 12px; border-radius: 10px; color: var(--ink-2); font-size: 15px; font-weight: 550; }
.nav > a:hover { background: var(--bg-soft); color: var(--ink); text-decoration: none; }
.langs { display: inline-flex; margin-left: 8px; padding: 3px; border: 1px solid var(--line); border-radius: 999px; }
.langs a { padding: 3px 10px; border-radius: 999px; color: var(--muted); font-size: 13px; font-weight: 600; }
.langs a:hover { color: var(--ink); text-decoration: none; }
.langs a[aria-current] { background: var(--ink); color: #fff; }
.btn { display: inline-flex; align-items: center; justify-content: center; border-radius: 999px; font-weight: 650; }
.btn-sm { padding: 8px 16px; font-size: 14px; }
.btn-primary { background: var(--ink); color: #fff; }
.btn-primary:hover { background: #262e45; color: #fff; text-decoration: none; }
.menu-btn { display: none; width: 42px; height: 42px; margin-left: auto; border: 0; background: transparent; border-radius: 10px; cursor: pointer; position: relative; }
.menu-btn i { position: absolute; left: 11px; right: 11px; height: 2px; background: var(--ink); border-radius: 2px; transition: transform .2s; }
.menu-btn i:first-of-type { top: 16px; }
.menu-btn i:last-of-type { top: 24px; }
.menu-btn[aria-expanded="true"] i:first-of-type { transform: translateY(4px) rotate(45deg); }
.menu-btn[aria-expanded="true"] i:last-of-type { transform: translateY(-4px) rotate(-45deg); }

/* ---------- 首屏 */
.hero { padding: clamp(48px, 8vw, 96px) 0 clamp(40px, 6vw, 72px); text-align: center; background: radial-gradient(1200px 520px at 50% 108%, #f3f6ff 0, rgba(243, 246, 255, 0) 70%); }
.kicker { color: var(--muted); font-size: 14px; font-weight: 600; letter-spacing: .04em; }
.hero h1 { max-width: 20em; margin: 14px auto 0; font-size: clamp(30px, 4.2vw, 46px); line-height: 1.22; letter-spacing: -.02em; font-weight: 700; }
.hero h1 .nw { display: inline-block; }
.h1-brand { display: block; margin-bottom: 6px; font-size: .62em; font-weight: 650; letter-spacing: -.01em; color: var(--ink-2); }
.hero .lead { max-width: 34em; margin: 20px auto 0; color: var(--muted); font-size: clamp(16px, 1.7vw, 18px); line-height: 1.75; }
.hero-stores { justify-content: center; margin-top: 30px; }
.hero-stores .store { min-width: 0; padding: 8px 16px; border-radius: 12px; }
.hero-stores .store-name { font-size: 14.5px; }
.hero-stores .store-sub { font-size: 12px; }
.hero-meta { margin-top: 14px; color: var(--muted); font-size: 13px; }

/* 彩虹桥 */
.bridge-art { position: relative; max-width: 1000px; margin: clamp(48px, 7vw, 80px) auto 0; }
.arc-box { position: relative; aspect-ratio: 1000 / 320; }
.arc { position: absolute; inset: 0; width: 100%; height: 100%; }
.spark-pill { position: absolute; left: 50%; top: 24.4%; transform: translate(-50%, -50%); display: inline-flex; align-items: center; gap: 6px; padding: 7px 14px 7px 10px; background: #fff; border: 1px solid var(--line); border-radius: 999px; box-shadow: var(--shadow); font-size: 14px; font-weight: 650; white-space: nowrap; }
.spark-pill .ico { width: 18px; height: 18px; color: #ff9f1c; }
.bubbles { position: absolute; top: 0; left: 16%; right: 16%; margin-top: 12%; display: grid; grid-template-columns: 1fr 1fr; gap: 20px; align-items: end; text-align: left; }
.bubble { padding: 14px 16px; background: #fff; border: 1px solid var(--line); border-radius: 18px; box-shadow: var(--shadow); }
.bubble-l { border-bottom-left-radius: 6px; margin-bottom: 26px; }
.bubble-r { border-bottom-right-radius: 6px; }
.b-orig { font-weight: 600; font-size: 15px; line-height: 1.5; }
.b-tr { margin-top: 8px; padding-top: 8px; border-top: 1px dashed var(--line); color: var(--muted); font-size: 14px; line-height: 1.5; }
.b-tag { display: inline-block; margin-right: 6px; padding: 0 7px; border-radius: 6px; background: var(--accent-soft); color: var(--accent-ink); font-size: 12px; font-weight: 650; line-height: 20px; vertical-align: 1px; }
.shores { display: flex; justify-content: space-between; gap: 16px; margin-top: 14px; }
.shore { display: flex; flex-direction: column; gap: 2px; text-align: left; font-size: 13px; color: var(--muted); }
.shore strong { color: var(--ink); font-size: 17px; }
.shore-r { text-align: right; }

/* ---------- 是什么 */
.what { padding: clamp(56px, 8vw, 96px) 0; border-top: 1px solid var(--line-2); }
.big { margin-top: 18px; font-size: clamp(17px, 1.9vw, 19px); color: var(--ink-2); }
.big strong { color: var(--ink); }
.facts { display: grid; grid-template-columns: repeat(4, 1fr); margin: 36px 0 0; border: 1px solid var(--line); border-radius: var(--radius); overflow: hidden; }
.facts div { padding: 18px 20px; border-left: 1px solid var(--line); }
.facts div:first-child { border-left: 0; }
.facts dt { color: var(--muted); font-size: 13px; font-weight: 600; }
.facts dd { margin: 4px 0 0; font-weight: 700; font-size: 16px; line-height: 1.4; }

/* ---------- 两个世界之间 */
.gap { padding: clamp(56px, 8vw, 96px) 0; background: var(--bg-soft); }
.gap-grid { display: grid; grid-template-columns: 1fr 28px 1fr; gap: 0 12px; margin-top: 36px; }
.gap-card { padding: 26px 26px 28px; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); }
.gap-card h3 { font-size: 24px; margin-top: 4px; }
.gap-card p:last-child { margin-top: 10px; color: var(--ink-2); }
.gap-who { color: var(--muted); font-size: 13px; font-weight: 650; letter-spacing: .02em; }
.gap-wall { align-self: stretch; width: 4px; margin: 8px auto; border-radius: 4px; background: repeating-linear-gradient(180deg, #c9cedb 0 10px, transparent 10px 18px); }
.gap-bridge { grid-column: 1 / -1; margin-top: 16px; position: relative; border: 0; box-shadow: var(--shadow); }
.gap-bridge::before { content: ""; position: absolute; inset: 0; padding: 2px; border-radius: inherit; background: var(--rainbow); -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0); -webkit-mask-composite: xor; mask-composite: exclude; pointer-events: none; }

/* ---------- 点亮四步 */
.how { padding: clamp(56px, 8vw, 96px) 0; }
.flow { list-style: none; display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; margin: 40px 0 0; padding: 0; counter-reset: s; position: relative; }
.flow::before { content: ""; position: absolute; left: 22px; right: 22px; top: 22px; height: 2px; background: var(--rainbow); opacity: .35; }
.flow li { position: relative; }
.flow .num { position: relative; display: grid; place-items: center; width: 44px; height: 44px; border-radius: 50%; background: #fff; border: 1.5px solid var(--ink); font-weight: 750; }
.flow li:last-child .num { background: var(--ink); color: #fff; }
.flow h3 { margin-top: 18px; font-size: 19px; }
.flow p { margin-top: 8px; color: var(--ink-2); font-size: 15px; }

/* ---------- 功能 */
.features { padding: clamp(56px, 8vw, 96px) 0; background: var(--bg-soft); }
.feat-list { list-style: none; display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; margin: 36px 0 0; padding: 0; }
.feat-list li { padding: 22px; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); }
.feat-list .ico { width: 28px; height: 28px; color: var(--accent); }
.feat-list h3 { margin-top: 14px; font-size: 17px; }
.feat-list p { margin-top: 6px; color: var(--ink-2); font-size: 15px; line-height: 1.6; }

/* ---------- 地区 */
.reach { padding: clamp(56px, 8vw, 96px) 0; text-align: center; }
.reach .sub { margin-inline: auto; }
.chips { list-style: none; display: flex; flex-wrap: wrap; justify-content: center; gap: 8px; margin: 28px 0 0; padding: 0; }
.chips li { padding: 6px 14px; border: 1px solid var(--line); border-radius: 999px; font-size: 14px; color: var(--ink-2); background: #fff; }
.chips li:nth-child(-n+4) { border-color: #ffc9ca; background: #fff6f6; }

/* ---------- FAQ */
.home-faq { padding: clamp(56px, 8vw, 96px) 0; border-top: 1px solid var(--line-2); }
.faq { margin-top: 28px; border-top: 1px solid var(--line); }
.faq details { border-bottom: 1px solid var(--line); }
.faq summary { position: relative; padding: 20px 40px 20px 0; cursor: pointer; list-style: none; font-weight: 650; font-size: 17px; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: ""; position: absolute; right: 6px; top: 50%; width: 10px; height: 10px; border-right: 2px solid var(--muted); border-bottom: 2px solid var(--muted); transform: translateY(-70%) rotate(45deg); transition: transform .2s; }
.faq details[open] summary::after { transform: translateY(-30%) rotate(225deg); }
.faq details p { padding: 0 0 22px; color: var(--ink-2); }

/* ---------- 下载 */
.download { padding: clamp(56px, 8vw, 96px) 0; background: var(--dark); color: #fff; }
.download h2 { color: #fff; }
.download .sub { color: #b8bfd3; }
.dl-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 40px; margin-top: 36px; }
.dl-grid h3 { margin-bottom: 14px; font-size: 15px; color: #b8bfd3; font-weight: 650; }
.stores { display: flex; flex-wrap: wrap; gap: 10px; }
.store { display: inline-flex; flex-direction: column; align-items: flex-start; min-width: 150px; padding: 10px 18px; border-radius: 14px; line-height: 1.3; border: 1px solid transparent; }
.store:hover { text-decoration: none; }
.store-name { font-weight: 700; font-size: 16px; }
.store-sub { font-size: 12.5px; opacity: .75; }
.store.btn-primary { background: var(--ink); color: #fff; }
.store.btn-primary:hover { background: #262e45; color: #fff; }
.store.btn-dark { background: #fff; color: var(--ink); border-color: var(--line); }
.store.btn-dark:hover { border-color: #c7ccd9; color: var(--ink); }
.download .store.btn-primary { background: #fff; color: var(--ink); }
.download .store.btn-dark { background: rgba(255, 255, 255, .06); color: #fff; border-color: rgba(255, 255, 255, .16); }
.download .store.btn-dark:hover { border-color: rgba(255, 255, 255, .4); }
.store.is-suggested { box-shadow: 0 0 0 3px rgba(42, 91, 246, .35); }
.dls { display: grid; grid-template-columns: repeat(auto-fill, minmax(150px, 1fr)); gap: 10px; }
.dl { position: relative; display: flex; flex-direction: column; padding: 10px 14px; border: 1px solid var(--line); border-radius: 12px; color: var(--ink); line-height: 1.35; }
.dl:hover { text-decoration: none; border-color: #c7ccd9; color: var(--ink); }
.dl-os { font-weight: 700; }
.dl-sub { font-size: 12.5px; color: var(--muted); }
.dl-ico { position: absolute; right: 12px; top: 10px; color: var(--muted); }
.dl.is-suggested { box-shadow: 0 0 0 3px rgba(42, 91, 246, .35); }
.download .dl { border-color: rgba(255, 255, 255, .16); color: #fff; }
.download .dl:hover { border-color: rgba(255, 255, 255, .4); }
.download .dl-sub, .download .dl-ico { color: #b8bfd3; }
.note { margin-top: 12px; color: var(--muted); font-size: 14px; }
.download .note { color: #b8bfd3; }

/* ---------- 内容页 */
.doc-hero { padding: clamp(40px, 6vw, 72px) 0 clamp(28px, 4vw, 44px); border-bottom: 1px solid var(--line-2); background: radial-gradient(900px 360px at 85% 0, #f3f6ff 0, rgba(243, 246, 255, 0) 70%); }
.doc-hero::after { content: ""; display: block; width: min(1120px, 100% - 32px); height: 3px; margin: clamp(28px, 4vw, 40px) auto 0; border-radius: 3px; background: var(--rainbow); opacity: .5; max-width: 120px; margin-left: max(16px, (100% - 1120px) / 2); }
.crumbs { display: flex; gap: 8px; color: var(--muted); font-size: 14px; }
.crumbs a { color: var(--muted); }
.doc-hero h1 { margin-top: 14px; max-width: 22em; font-size: clamp(30px, 4.4vw, 46px); letter-spacing: -.02em; font-weight: 800; }
.doc-hero .lead { margin-top: 16px; max-width: 40em; color: var(--ink-2); font-size: clamp(17px, 1.9vw, 19px); }
.doc { display: grid; grid-template-columns: 220px minmax(0, 1fr); gap: 56px; padding: clamp(36px, 5vw, 56px) 0 clamp(56px, 7vw, 88px); }
.toc { position: sticky; top: 88px; align-self: start; font-size: 14px; }
.toc p { color: var(--muted); font-weight: 650; font-size: 13px; }
.toc ol { list-style: none; margin: 10px 0 0; padding: 0; border-left: 1px solid var(--line); }
.toc a { display: block; padding: 5px 0 5px 14px; color: var(--ink-2); }
.toc a:hover { color: var(--accent); text-decoration: none; }
.prose { max-width: 760px; font-size: 17px; }
.prose > * + * { margin-top: 18px; }
.prose h2 { margin-top: 48px; font-size: clamp(22px, 2.6vw, 28px); }
.prose h2:first-child { margin-top: 0; }
.prose ul, .prose ol:not(.steps) { padding-left: 1.3em; }
.prose li + li { margin-top: 8px; }
.prose strong { color: var(--ink); }
.prose p, .prose li { color: var(--ink-2); }
.steps { list-style: none; padding: 0; display: grid; gap: 12px; }
.steps li { display: grid; grid-template-columns: 40px 1fr; gap: 14px; padding: 18px 20px; border: 1px solid var(--line); border-radius: var(--radius-sm); }
.steps .num { display: grid; place-items: center; width: 34px; height: 34px; border-radius: 50%; background: var(--ink); color: #fff; font-weight: 700; font-size: 15px; }
.steps h3 { font-size: 17px; }
.steps p { margin-top: 4px; font-size: 15.5px; }
.table { overflow-x: auto; border: 1px solid var(--line); border-radius: var(--radius-sm); -webkit-overflow-scrolling: touch; }
.table table { width: 100%; border-collapse: collapse; font-size: 15px; }
.table th, .table td { min-width: 6.5em; padding: 12px 16px; text-align: left; vertical-align: top; border-bottom: 1px solid var(--line); }
.table thead th { background: var(--bg-soft); font-weight: 650; white-space: nowrap; }
.table tbody th { font-weight: 650; color: var(--ink); }
.table td { color: var(--ink-2); }
.table tr:last-child td, .table tr:last-child th { border-bottom: 0; }
.prose .stores { margin-top: 16px; }
.related { padding: clamp(48px, 6vw, 72px) 0; background: var(--bg-soft); }
.related h2 { font-size: 24px; }
.scene-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 16px; margin-top: 24px; }
.scene { position: relative; display: block; padding: 22px 48px 22px 22px; background: #fff; border: 1px solid var(--line); border-radius: var(--radius); color: var(--ink); }
.scene:hover { text-decoration: none; border-color: #c7ccd9; color: var(--ink); }
.scene h3 { font-size: 17px; }
.scene p { margin-top: 6px; color: var(--muted); font-size: 14.5px; display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical; overflow: hidden; }
.scene .arrow { position: absolute; right: 20px; top: 22px; color: var(--muted); }

/* ---------- 页脚 */
.footer { padding: 56px 0 32px; border-top: 1px solid var(--line-2); font-size: 14px; }
.footer-top { display: grid; grid-template-columns: 1.1fr 2fr; gap: 48px; }
.footer-brand p { margin-top: 12px; color: var(--muted); max-width: 26em; }
.footer-cols { display: grid; grid-template-columns: repeat(4, 1fr); gap: 24px; }
.footer-cols h2 { font-size: 13px; color: var(--ink); font-weight: 700; }
.footer-cols ul { list-style: none; margin: 12px 0 0; padding: 0; }
.footer-cols li + li { margin-top: 8px; }
.footer a { color: var(--muted); }
.footer a:hover { color: var(--ink); }
.footer-bottom { display: flex; flex-wrap: wrap; gap: 8px 20px; margin-top: 40px; padding-top: 20px; border-top: 1px solid var(--line-2); color: var(--muted); font-size: 13px; }

/* ---------- 响应式 */
@media (max-width: 960px) {
  .feat-list { grid-template-columns: repeat(2, 1fr); }
  .flow { grid-template-columns: repeat(2, 1fr); gap: 28px 16px; }
  .flow::before { display: none; }
  .facts { grid-template-columns: 1fr 1fr; }
  .facts div:nth-child(3) { border-left: 0; }
  .facts div:nth-child(n+3) { border-top: 1px solid var(--line); }
  .doc { grid-template-columns: minmax(0, 1fr); gap: 0; }
  .toc { display: none; }
  .footer-top { grid-template-columns: 1fr; gap: 32px; }
}
@media (max-width: 760px) {
  .menu-btn { display: block; }
  .nav-cta { display: none; }
  .nav { position: absolute; left: 0; right: 0; top: 64px; display: none; flex-direction: column; align-items: stretch; gap: 0; padding: 8px 16px 16px; background: #fff; border-bottom: 1px solid var(--line); box-shadow: 0 12px 24px rgba(13, 18, 34, .06); }
  .nav.is-open { display: flex; }
  .nav > a { padding: 12px 4px; border-bottom: 1px solid var(--line-2); border-radius: 0; font-size: 16px; }
  .langs { align-self: flex-start; margin: 14px 0 0; }
  .arc-box { aspect-ratio: 1000 / 380; }
  .spark-pill { top: 21%; font-size: 13px; }
  .bubbles { position: static; grid-template-columns: 1fr; gap: 12px; margin-top: 20px; }
  .bubble-l { margin: 0 14% 0 0; }
  .bubble-r { margin: 0 0 0 14%; }
  .shore span { font-size: 12px; }
  .gap-grid { grid-template-columns: 1fr; gap: 12px; }
  .gap-wall { width: auto; height: 4px; margin: 0 24px; background: repeating-linear-gradient(90deg, #c9cedb 0 10px, transparent 10px 18px); }
  .gap-bridge { margin-top: 4px; }
  .dl-grid { grid-template-columns: 1fr; gap: 28px; }
  .scene-grid, .scene-grid.three { grid-template-columns: 1fr; }
  .footer-cols { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 520px) {
  .feat-list { grid-template-columns: 1fr; }
  .flow { grid-template-columns: 1fr; }
  .store { flex: 1 1 calc(50% - 5px); min-width: 0; }
  .facts { grid-template-columns: 1fr 1fr; }
  .facts div { padding: 14px; }
  .shore span { display: none; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } * { transition: none !important; } }