:root {
  --ink: #17202a;
  --muted: #64717d;
  --paper: #f5fbff;
  --card: rgba(255, 255, 255, 0.88);
  --line: #d8e9f4;
  --blue: #1399d6;
  --blue-deep: #0877b5;
  --yellow: #ffd85c;
  --shadow: 0 20px 60px rgba(17, 115, 164, 0.13);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at 8% 8%, rgba(255, 216, 92, .26), transparent 22rem),
    radial-gradient(circle at 90% 18%, rgba(19, 153, 214, .16), transparent 28rem),
    var(--paper);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  font-size: 16px;
  line-height: 1.75;
}
a { color: inherit; }
.shell { width: min(1120px, calc(100% - 40px)); margin: 0 auto; }
.site-header {
  position: sticky; top: 0; z-index: 10;
  border-bottom: 1px solid rgba(216, 233, 244, .8);
  background: rgba(245, 251, 255, .86);
  backdrop-filter: blur(18px);
}
.nav { min-height: 72px; display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.brand { display: flex; align-items: center; gap: 12px; text-decoration: none; font-weight: 800; }
.brand-mark { display: grid; place-items: center; width: 42px; height: 42px; border-radius: 14px; color: white; background: var(--blue); box-shadow: 0 9px 22px rgba(19,153,214,.25); font-size: 25px; }
.brand small { display: block; color: var(--muted); font-size: .72rem; font-weight: 600; letter-spacing: .08em; }
.nav-links { display: flex; align-items: center; gap: 24px; }
.nav-links a { text-decoration: none; color: #3f4c57; font-size: .93rem; }
.nav-links a:hover { color: var(--blue-deep); }
.menu-button { display: none; border: 0; background: transparent; font-size: 1.5rem; }

.hero { min-height: 650px; display: grid; grid-template-columns: 1.08fr .92fr; align-items: center; gap: 70px; padding: 72px 0; }
.eyebrow { color: var(--blue-deep); font-weight: 800; letter-spacing: .14em; font-size: .82rem; text-transform: uppercase; }
h1 { margin: 14px 0 22px; font-size: clamp(2.6rem, 7vw, 5.8rem); line-height: .98; letter-spacing: -.055em; }
.hero h1 span { color: var(--blue); }
.lead { max-width: 640px; color: var(--muted); font-size: 1.15rem; }
.actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 32px; }
.button { display: inline-flex; align-items: center; justify-content: center; min-height: 48px; padding: 0 22px; border-radius: 15px; background: var(--blue); color: white; font-weight: 750; text-decoration: none; box-shadow: 0 10px 24px rgba(19,153,214,.22); }
.button.secondary { color: var(--ink); background: white; border: 1px solid var(--line); box-shadow: none; }
.pixel-board { aspect-ratio: 1; display: grid; grid-template-columns: repeat(9, 1fr); gap: 7px; padding: 28px; border: 1px solid rgba(216,233,244,.9); border-radius: 36px; background: rgba(255,255,255,.7); box-shadow: var(--shadow); transform: rotate(2deg); }
.pixel { border-radius: 50%; background: #dceef7; box-shadow: inset 0 -3px 5px rgba(0,80,120,.1); }
.pixel.blue { background: var(--blue); }
.pixel.yellow { background: var(--yellow); }
.pixel.dark { background: #233947; }
.section { padding: 90px 0; }
.section-title { max-width: 620px; margin-bottom: 34px; }
.section h2 { margin: 0 0 12px; font-size: clamp(2rem, 4vw, 3.4rem); line-height: 1.08; letter-spacing: -.035em; }
.section-title p, .muted { color: var(--muted); }
.feature-grid, .link-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; }
.card { padding: 28px; border: 1px solid var(--line); border-radius: 24px; background: var(--card); box-shadow: 0 12px 35px rgba(20,90,125,.07); }
.card h3 { margin: 10px 0 8px; font-size: 1.22rem; }
.card p { margin: 0; color: var(--muted); }
.icon { width: 42px; height: 42px; display: grid; place-items: center; border-radius: 13px; background: #e4f6ff; color: var(--blue-deep); font-weight: 900; }
.link-card { position: relative; min-height: 180px; display: flex; flex-direction: column; justify-content: space-between; text-decoration: none; transition: transform .2s ease, border-color .2s ease; }
.link-card:hover { transform: translateY(-4px); border-color: #98d6f2; }
.link-card .arrow { align-self: flex-end; font-size: 1.4rem; color: var(--blue); }

.doc-wrap { width: min(840px, calc(100% - 36px)); margin: 0 auto; padding: 72px 0 100px; }
.doc-head { margin-bottom: 34px; }
.doc-head h1 { font-size: clamp(2.4rem, 7vw, 4.5rem); }
.updated { color: var(--muted); font-size: .92rem; }
.doc { padding: clamp(24px, 5vw, 54px); border: 1px solid var(--line); border-radius: 28px; background: white; box-shadow: var(--shadow); }
.doc h2 { margin: 2.1em 0 .55em; font-size: 1.35rem; line-height: 1.35; }
.doc h2:first-child { margin-top: 0; }
.doc p, .doc li { color: #3e4b55; }
.doc ul, .doc ol { padding-left: 1.3em; }
.notice { padding: 18px 20px; border-left: 4px solid var(--blue); border-radius: 12px; background: #edf8fd; color: #34515f; }
.support-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin: 24px 0; }
.faq { border-top: 1px solid var(--line); }
.faq details { border-bottom: 1px solid var(--line); padding: 18px 0; }
.faq summary { cursor: pointer; font-weight: 750; }
.faq p { margin-bottom: 0; }
.site-footer { border-top: 1px solid var(--line); padding: 34px 0 48px; color: var(--muted); }
.footer-inner { display: flex; justify-content: space-between; gap: 24px; }
.footer-links { display: flex; flex-wrap: wrap; gap: 16px; }
.footer-links a { text-decoration: none; }

@media (max-width: 820px) {
  .menu-button { display: block; }
  .nav-links { display: none; position: absolute; inset: 72px 20px auto; padding: 18px; flex-direction: column; align-items: stretch; border: 1px solid var(--line); border-radius: 18px; background: white; box-shadow: var(--shadow); }
  .nav-links.open { display: flex; }
  .hero { min-height: auto; grid-template-columns: 1fr; gap: 40px; padding-top: 52px; }
  .pixel-board { width: min(92%, 430px); margin: 0 auto; }
  .feature-grid, .link-grid, .support-grid { grid-template-columns: 1fr; }
  .section { padding: 64px 0; }
  .footer-inner { flex-direction: column; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .link-card { transition: none; }
}