:root {
  --blue: #1D6FF2;
  --blue-deep: #0F56D0;
  --ink: #12263F;
  --ink-soft: #4A6076;
  --mist: #F3F8FE;
  --line: #DCE7F6;
  --white: #FFFFFF;
  --ok: #16A34A;
  --radius: 14px;
  --font-display: "Sora", "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-body: "Manrope", "PingFang SC", "Microsoft YaHei", sans-serif;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-body);
  color: var(--ink);
  background: var(--white);
  line-height: 1.7;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

/* ---------- i18n ---------- */
body[data-lang="zh"] .lang-en { display: none; }
body[data-lang="en"] .lang-zh { display: none; }

/* ---------- layout ---------- */
.wrap { max-width: 1080px; margin: 0 auto; padding: 0 24px; }

/* ---------- header ---------- */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: rgba(255,255,255,.92);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--line);
}
.header-inner {
  display: flex; align-items: center; justify-content: space-between;
  height: 64px; gap: 16px;
}
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; }
.brand img { width: 34px; height: 34px; border-radius: 8px; }
.brand-name {
  font-family: var(--font-display);
  font-weight: 700; font-size: 18px; color: var(--ink); letter-spacing: .2px;
}
.brand-name span { color: var(--blue); }

.nav { display: flex; align-items: center; gap: 4px; }
.nav a {
  text-decoration: none; color: var(--ink-soft); font-size: 14.5px;
  padding: 8px 12px; border-radius: 8px; transition: color .15s, background .15s;
}
.nav a:hover, .nav a[aria-current="page"] { color: var(--blue-deep); background: var(--mist); }
.nav a:focus-visible { outline: 2px solid var(--blue); outline-offset: 2px; }

.lang-btn {
  border: 1px solid var(--line); background: var(--white); color: var(--ink-soft);
  font-family: var(--font-body); font-size: 13.5px; font-weight: 600;
  padding: 7px 14px; border-radius: 999px; cursor: pointer;
  transition: border-color .15s, color .15s;
}
.lang-btn:hover { border-color: var(--blue); color: var(--blue-deep); }
.lang-btn:focus-visible { outline: 2px solid var(--blue); outline-offset: 2px; }

.nav-toggle { display: none; }

/* ---------- hero ---------- */
.hero {
  background:
    radial-gradient(900px 420px at 85% -10%, rgba(29,111,242,.10), transparent 60%),
    radial-gradient(700px 380px at -10% 110%, rgba(29,111,242,.07), transparent 60%),
    var(--mist);
  border-bottom: 1px solid var(--line);
  padding: 72px 0 64px;
}
.hero-grid { display: grid; grid-template-columns: 1.15fr .85fr; gap: 48px; align-items: center; }
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px;
  font-size: 13px; font-weight: 700; letter-spacing: .12em; text-transform: uppercase;
  color: var(--blue-deep); margin-bottom: 18px;
}
.eyebrow::before { content: ""; width: 22px; height: 2px; background: var(--blue); border-radius: 2px; }
.hero h1 {
  font-family: var(--font-display);
  font-size: clamp(30px, 4.4vw, 46px);
  line-height: 1.22; letter-spacing: -.01em; margin-bottom: 18px;
}
.hero h1 em { font-style: normal; color: var(--blue); }
.hero .lede { color: var(--ink-soft); font-size: 17px; max-width: 54ch; margin-bottom: 28px; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; }
.hero-shot {
  background: var(--white); border: 1px solid var(--line); border-radius: 18px;
  padding: 10px; box-shadow: 0 18px 40px -22px rgba(15,86,208,.28);
}
.hero-shot img { display: block; width: 100%; border-radius: 10px; }

/* ---------- buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 8px;
  font-family: var(--font-body); font-weight: 700; font-size: 15px;
  padding: 12px 22px; border-radius: 10px; text-decoration: none; cursor: pointer;
  border: 1px solid transparent; transition: transform .15s, box-shadow .15s, background .15s;
}
.btn:focus-visible { outline: 2px solid var(--blue); outline-offset: 2px; }
.btn-primary { background: var(--blue); color: #fff; box-shadow: 0 10px 24px -12px rgba(29,111,242,.55); }
.btn-primary:hover { background: var(--blue-deep); transform: translateY(-1px); }
.btn-ghost { background: var(--white); color: var(--blue-deep); border-color: var(--line); }
.btn-ghost:hover { border-color: var(--blue); }

/* ---------- sections ---------- */
.section { padding: 64px 0; }
.section.alt { background: var(--mist); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.section-head { max-width: 640px; margin-bottom: 40px; }
.section-head h2 {
  font-family: var(--font-display);
  font-size: clamp(24px, 3vw, 32px); letter-spacing: -.01em;
  margin-bottom: 10px;
}
.section-head p { color: var(--ink-soft); }

/* signature: data-flow divider */
.flow-divider { display: flex; align-items: center; gap: 0; margin: 8px 0 28px; }
.flow-divider .node {
  width: 10px; height: 10px; border-radius: 50%;
  background: var(--white); border: 2.5px solid var(--blue); flex: none;
}
.flow-divider .node.solid { background: var(--blue); }
.flow-divider .dash {
  flex: 1; height: 0; border-top: 2px dashed var(--line);
  position: relative; overflow: hidden;
}
.flow-divider .dash::after {
  content: ""; position: absolute; top: -2px; left: -30%; width: 30%;
  border-top: 2px dashed var(--blue);
  animation: flow 3.2s linear infinite;
}
@keyframes flow { to { left: 100%; } }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .flow-divider .dash::after { animation: none; }
}

/* ---------- feature cards ---------- */
.feature-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 22px; }
.feature-card {
  background: var(--white); border: 1px solid var(--line); border-radius: var(--radius);
  overflow: hidden; display: flex; flex-direction: column;
  transition: transform .2s, box-shadow .2s;
}
.feature-card:hover { transform: translateY(-3px); box-shadow: 0 16px 32px -20px rgba(15,86,208,.30); }
.feature-card img { width: 100%; aspect-ratio: 16/10; object-fit: cover; }
.feature-body { padding: 20px 22px 24px; }
.feature-body h3 { font-family: var(--font-display); font-size: 19px; margin-bottom: 8px; }
.feature-body p { color: var(--ink-soft); font-size: 15px; }
.tag-row { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 14px; }
.tag {
  font-size: 12.5px; font-weight: 600; color: var(--blue-deep);
  background: var(--mist); border: 1px solid var(--line);
  padding: 4px 12px; border-radius: 999px;
}

/* ---------- steps (OAuth) ---------- */
.steps { display: grid; grid-template-columns: repeat(3, 1fr); gap: 22px; counter-reset: step; }
.step {
  background: var(--white); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 26px 24px; position: relative;
}
.step::before {
  counter-increment: step; content: "0" counter(step);
  font-family: var(--font-display); font-weight: 700; font-size: 15px;
  color: var(--blue); letter-spacing: .08em;
  display: inline-block; margin-bottom: 14px;
  border: 1.5px solid var(--line); border-radius: 8px; padding: 4px 10px;
  background: var(--mist);
}
.step h3 { font-family: var(--font-display); font-size: 17.5px; margin-bottom: 8px; }
.step p { color: var(--ink-soft); font-size: 14.5px; }

/* ---------- compliance list ---------- */
.promise-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 18px; }
.promise {
  display: flex; gap: 14px; align-items: flex-start;
  background: var(--white); border: 1px solid var(--line); border-radius: var(--radius);
  padding: 20px 22px;
}
.promise svg { flex: none; margin-top: 3px; }
.promise h3 { font-size: 16px; margin-bottom: 4px; font-family: var(--font-display); }
.promise p { color: var(--ink-soft); font-size: 14.5px; }

/* ---------- legal / prose ---------- */
.prose { max-width: 800px; }
.prose h2 { font-family: var(--font-display); font-size: 26px; margin: 44px 0 14px; }
.prose h2:first-child { margin-top: 0; }
.prose h3 { font-family: var(--font-display); font-size: 18px; margin: 28px 0 10px; }
.prose p, .prose li { color: var(--ink-soft); font-size: 15.5px; }
.prose ul, .prose ol { padding-left: 22px; margin: 10px 0; }
.prose li { margin-bottom: 6px; }
.prose strong { color: var(--ink); }
.updated {
  display: inline-block; font-size: 13px; font-weight: 600; color: var(--blue-deep);
  background: var(--mist); border: 1px solid var(--line);
  padding: 4px 12px; border-radius: 999px; margin-bottom: 8px;
}

/* ---------- contact card ---------- */
.contact-card {
  background: linear-gradient(135deg, #0F56D0, #1D6FF2);
  color: #fff; border-radius: 18px; padding: 40px 44px;
  display: flex; justify-content: space-between; align-items: center; gap: 24px; flex-wrap: wrap;
}
.contact-card h2 { font-family: var(--font-display); font-size: 26px; margin-bottom: 8px; }
.contact-card p { opacity: .9; font-size: 15px; }
.contact-card a.mail {
  display: inline-block; background: #fff; color: var(--blue-deep);
  font-weight: 700; text-decoration: none; padding: 12px 22px; border-radius: 10px;
}
.contact-card a.mail:focus-visible { outline: 2px solid #fff; outline-offset: 3px; }

/* ---------- table ---------- */
.scope-table { width: 100%; border-collapse: collapse; margin: 16px 0; font-size: 14.5px; }
.scope-table th, .scope-table td {
  text-align: left; padding: 12px 14px; border-bottom: 1px solid var(--line); vertical-align: top;
}
.scope-table th { font-family: var(--font-display); font-size: 13.5px; color: var(--ink); background: var(--mist); }
.scope-table td { color: var(--ink-soft); }
.scope-table code {
  font-family: Consolas, monospace; font-size: 13px;
  background: var(--mist); border: 1px solid var(--line); border-radius: 6px; padding: 2px 7px;
  color: var(--blue-deep); white-space: nowrap;
}

/* ---------- FAQ ---------- */
.faq-item { border: 1px solid var(--line); border-radius: var(--radius); background: var(--white); margin-bottom: 14px; }
.faq-item summary {
  cursor: pointer; padding: 18px 22px; font-weight: 700; font-size: 15.5px;
  font-family: var(--font-display); list-style: none; position: relative;
}
.faq-item summary::-webkit-details-marker { display: none; }
.faq-item summary::after { content: "+"; position: absolute; right: 22px; color: var(--blue); font-size: 20px; }
.faq-item[open] summary::after { content: "–"; }
.faq-item .faq-body { padding: 0 22px 18px; color: var(--ink-soft); font-size: 14.5px; }
.faq-item summary:focus-visible { outline: 2px solid var(--blue); outline-offset: -2px; border-radius: var(--radius); }

/* ---------- footer ---------- */
.site-footer { background: #0C1B30; color: #B9C8DB; margin-top: 64px; }
.footer-inner {
  display: grid; grid-template-columns: 1.4fr 1fr 1fr 1fr; gap: 32px; padding: 48px 0 36px;
}
.site-footer .brand-name { color: #fff; }
.footer-desc { font-size: 13.5px; margin-top: 12px; max-width: 30ch; opacity: .8; }
.site-footer h4 {
  color: #fff; font-size: 13px; letter-spacing: .1em; text-transform: uppercase;
  margin-bottom: 14px; font-family: var(--font-display);
}
.site-footer a { color: #B9C8DB; text-decoration: none; font-size: 14px; display: block; padding: 4px 0; }
.site-footer a:hover { color: #fff; }
.site-footer a:focus-visible { outline: 2px solid var(--blue); outline-offset: 2px; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,.12); padding: 18px 0;
  font-size: 13px; display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; opacity: .75;
}

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  .hero-grid { grid-template-columns: 1fr; gap: 32px; }
  .feature-grid, .promise-grid { grid-template-columns: 1fr; }
  .steps { grid-template-columns: 1fr; }
  .footer-inner { grid-template-columns: 1fr 1fr; }
  .nav {
    display: none; position: absolute; top: 64px; left: 0; right: 0;
    background: var(--white); border-bottom: 1px solid var(--line);
    flex-direction: column; align-items: stretch; padding: 10px 16px 16px; gap: 2px;
  }
  .nav.open { display: flex; }
  .nav a { padding: 12px; }
  .nav-toggle {
    display: inline-flex; align-items: center; justify-content: center;
    width: 40px; height: 40px; border: 1px solid var(--line); border-radius: 10px;
    background: var(--white); cursor: pointer;
  }
  .nav-toggle:focus-visible { outline: 2px solid var(--blue); outline-offset: 2px; }
}
@media (max-width: 560px) {
  .footer-inner { grid-template-columns: 1fr; }
  .contact-card { padding: 30px 26px; }
  .section { padding: 48px 0; }
}