:root {
  --i4: #007aff;
  --i4-hover: #0074f2;
  --i4-active: #006ee5;
  --i4-deep: #236ee7;
  --ink: #333333;
  --ink-2: #5c5c5c;
  --muted: #666666;
  --line: #eeeeee;
  --paper: #f5f5f7;
  --max: 1180px;
  --header: 76px;
  --sans: "PingFang SC", "Microsoft YaHei", "Segoe UI", "Noto Sans SC", "Helvetica Neue", sans-serif;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; }
html, body { margin: 0; padding: 0; }
body {
  font-family: var(--sans);
  color: var(--ink);
  background: #fff;
  line-height: 1.7;
  padding-top: var(--header);
}
body:not(:has(.masthead)) { padding-top: 0; }
img, svg { display: block; max-width: 100%; height: auto; }
a { color: var(--i4); text-decoration: none; }
a:hover { color: var(--i4-hover); }
h1, h2, h3, p, ul, ol, figure { margin: 0; }
button { font: inherit; color: inherit; background: none; border: 0; padding: 0; cursor: pointer; }
:focus-visible { outline: 2px solid var(--i4); outline-offset: 2px; }

.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0;
}
.skip { position: absolute; left: -999px; top: 0; }
.skip:focus { left: 12px; top: 12px; z-index: 80; background: #fff; color: var(--ink); padding: 8px 12px; }

.wrap { width: min(var(--max), calc(100% - 40px)); margin: 0 auto; }

.masthead {
  position: fixed; top: 0; left: 0; z-index: 40;
  width: 100%; height: var(--header);
  background: rgba(255, 255, 255, 0.85);
  -webkit-backdrop-filter: blur(20px);
  backdrop-filter: blur(20px);
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}
.masthead-inner {
  height: var(--header);
  display: flex; align-items: center; justify-content: space-between; gap: 16px;
}
.brand, .head-lf { display: flex; align-items: center; gap: 10px; color: inherit; min-width: 0; }
.brand:hover { color: inherit; }
.brand-mark, .logo img { width: 36px; height: 36px; flex: 0 0 auto; }
.logo { width: 36px; height: 36px; }
.brand-name { font-size: 16px; font-weight: 700; color: #000; }
.brand-tag { display: block; font-size: 11px; color: #666; }

.nav { display: none; align-items: center; padding-left: 12px; }
.nav a {
  height: 36px; line-height: 36px; font-size: 14px;
  color: rgba(0, 0, 0, 0.85); border-radius: 100px; padding: 0 16px;
  white-space: nowrap;
}
.nav a:hover { color: rgba(0, 0, 0, 0.55); }
.nav a[aria-current="page"] { color: #000; background: rgba(0, 0, 0, 0.05); }

.tools { display: flex; align-items: center; gap: 10px; }
.menu-btn {
  width: 42px; height: 42px;
  display: inline-flex; align-items: center; justify-content: center;
  border: 1px solid var(--line); border-radius: 10px; color: #333;
}
.drawer { display: none; position: fixed; inset: 0; z-index: 50; background: rgba(0, 0, 0, 0.45); }
.drawer.is-open { display: flex; justify-content: flex-end; }
.drawer-panel {
  width: min(300px, 86vw); height: 100%; background: #fff;
  padding: 80px 22px 28px; display: flex; flex-direction: column; gap: 4px;
}
.drawer-panel a { min-height: 44px; display: flex; align-items: center; color: #333; font-weight: 600; }

.dl-btn, .dl-btn-lg {
  display: inline-flex; align-items: center; justify-content: center;
  background: var(--i4); color: #fff !important; font-weight: 700;
}
.dl-btn { min-width: 108px; height: 36px; padding: 0 16px; border-radius: 8px; font-size: 14px; }
.dl-btn-lg { width: 240px; height: 52px; border-radius: 10px; font-size: 16px; }
.dl-btn:hover, .dl-btn-lg:hover { background: var(--i4-hover); color: #fff !important; }

.notice-bar {
  background: var(--paper); color: #666; font-size: 13px;
  padding: 8px 0; border-bottom: 1px solid #eee;
}

.band { padding: 48px 0 72px; }
.page { padding: 36px 0 72px; max-width: 760px; }
.crumbs { font-size: 13px; color: #999; margin-bottom: 16px; }
.crumbs a { color: #999; }
.page h1 { font-size: clamp(26px, 4vw, 36px); margin-bottom: 12px; }
.page h2 { font-size: 22px; margin: 28px 0 10px; }
.page p, .page li { color: var(--ink-2); margin-bottom: 12px; }

.edition {
  display: flex; justify-content: space-between; gap: 16px; align-items: center;
  background: rgba(0, 0, 0, 0.05); border-radius: 10px;
  padding: 18px 22px; margin: 12px 0; flex-wrap: wrap;
}
.edition h3 { margin: 0 0 4px; font-size: 16px; }
.edition p { margin: 0; font-size: 13px; color: #666; }

.steps { list-style: none; padding: 0; display: grid; gap: 14px; counter-reset: step; }
.steps li {
  background: #fff; border: 1px solid var(--line); border-radius: 12px;
  padding: 16px 16px 16px 62px; position: relative; color: var(--ink-2);
}
.steps li::before {
  counter-increment: step; content: counter(step);
  position: absolute; left: 16px; top: 16px;
  width: 32px; height: 32px; border-radius: 50%;
  background: var(--i4); color: #fff;
  display: grid; place-items: center; font-weight: 700;
}

.faq details { border-bottom: 1px solid var(--line); padding: 14px 0; }
.faq summary { cursor: pointer; font-weight: 700; font-size: 16px; }
.faq details p { margin-top: 8px; color: var(--ink-2); }

.site-footer {
  background: #fff; color: #666; padding: 46px 0 28px;
  border-top: 1px solid #f0f0f0; font-size: 13px;
}
.site-footer a { color: #333; }
.site-footer h2, .site-footer h3 { color: #111; font-size: 15px; margin-bottom: 8px; }
.footer-grid { display: grid; gap: 24px; }
.legal { margin-top: 22px; color: #5c5c5c; font-size: 13px; }

.modal {
  display: none; position: fixed; inset: 0; z-index: 60;
  background: rgba(0, 0, 0, 0.55);
  align-items: center; justify-content: center; padding: 20px;
}
.modal.is-open { display: flex; }
.modal-box {
  width: min(720px, 100%); background: #fff; border-radius: 16px; overflow: hidden;
  display: grid; grid-template-columns: 168px 1fr; max-height: min(86vh, 560px);
}
.modal-side { background: #f5f5f7; padding: 18px 10px; }
.modal-side button {
  width: 100%; display: flex; align-items: center; gap: 10px;
  padding: 12px; border-radius: 10px; color: #333; font-weight: 600;
}
.modal-side button.is-on { background: #fff; color: var(--i4); }
.modal-main { padding: 24px 22px; overflow: auto; }
.modal-main[hidden] { display: none !important; }
.modal-top { display: flex; justify-content: space-between; align-items: center; padding: 18px 22px 0; }
.modal-close { width: 36px; height: 36px; font-size: 22px; color: #666; }

@media (min-width: 880px) {
  .menu-btn { display: none; }
  .nav { display: flex; }
  .footer-grid { grid-template-columns: 1.6fr 1fr 1fr; }
}
@media (max-width: 879px) {
  .brand-tag { display: none; }
  .modal-box { grid-template-columns: 1fr; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } }