:root {
  color-scheme: light;
  --ink: #222f43;
  --muted: #5e6c80;
  --blue: #2563b9;
  --blue-hover: #1b4e96;
  --line: #e1e8f1;
  --surface: #fff;
  --soft: #eef4fd;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 96px; }
body { margin: 0; color: var(--ink); background: #f6f8fb; font: 16px/1.7 -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif; }
h1,h2,h3,p { margin: 0; }
a { color: var(--blue); text-underline-offset: 4px; }
button { font: inherit; cursor: pointer; }
a,button { touch-action: manipulation; }
a:focus-visible,button:focus-visible { outline: 3px solid var(--blue); outline-offset: 4px; }
[hidden] { display: none !important; }
.skip-link { position: fixed; top: -100px; left: 16px; z-index: 50; background: white; padding: 12px; }
.skip-link:focus { top: 8px; }
.topbar { position: sticky; top: 0; z-index: 10; min-height: 76px; padding: 12px max(24px, calc((100% - 1080px) / 2)); display: flex; justify-content: space-between; align-items: center; gap: 20px; border-bottom: 1px solid var(--line); background: var(--surface); }
.brand { display: inline-flex; align-items: center; min-height: 44px; color: var(--ink); text-decoration: none; font-size: 21px; font-weight: 800; white-space: nowrap; }
.brand span { font-size: 14px; font-weight: 400; color: var(--muted); border-left: 1px solid var(--line); margin-left: 16px; padding-left: 16px; }
.topbar nav { display: flex; gap: 8px; }
.topbar nav a { min-height: 44px; padding: 8px 14px; border-radius: 10px; display: inline-flex; align-items: center; text-decoration: none; color: var(--muted); white-space: nowrap; }
.topbar nav a:hover { background: var(--soft); color: var(--blue); }
.shell { max-width: 1080px; margin: auto; padding: 28px 0 56px; }
.intro { display: flex; align-items: center; justify-content: space-between; gap: 24px; padding: 24px 32px; margin-bottom: 32px; border: 1px solid #dce6f4; border-radius: 24px; background: linear-gradient(115deg, #eff5ff, #f9fbff 60%, #eff8f4); }
.eyebrow { font-size: 12px; font-weight: 750; letter-spacing: .09em; color: var(--blue); margin-bottom: 6px; }
.intro .eyebrow { font-size: 14px; letter-spacing: .04em; }
h1 { font-size: clamp(28px, 3.4vw, 40px); line-height: 1.4; letter-spacing: -.025em; margin: 6px 0 12px; }
.intro-copy { color: var(--muted); }
.intro-links { display: flex; gap: 20px; margin-top: 22px; flex-wrap: wrap; }
.intro-links a { min-height: 44px; display: inline-flex; align-items: center; gap: 8px; text-decoration: none; font-weight: 650; }
.intro-links a:hover { text-decoration: underline; }
.intro-art { display: grid; justify-items: center; gap: 8px; min-width: 190px; color: var(--muted); font-size: 13px; }
.intro-art img { width: 128px; height: 128px; object-fit: contain; }
.section-heading { display: flex; align-items: center; justify-content: space-between; gap: 16px; margin-bottom: 20px; }
h2 { font-size: 24px; line-height: 1.45; }
.section-heading > p,.section-label { font-size: 14px; color: var(--muted); }
.platform-grid,.cloud-grid { display: grid; grid-template-columns: repeat(2,minmax(0,1fr)); gap: 20px; }
.platform-card { display: flex; flex-direction: column; background: var(--surface); border: 1px solid var(--line); border-radius: 20px; padding: 28px; box-shadow: 0 6px 22px #233b6110; }
.card-top { display: flex; align-items: center; justify-content: space-between; margin-bottom: 20px; }
.platform-symbol { display: grid; place-items: center; width: 54px; height: 54px; border-radius: 15px; background: var(--soft); color: var(--blue); font-weight: 800; font-size: 18px; letter-spacing: -.03em; }
.android-card .platform-symbol { background: #edf7f2; color: #26724f; }
.edition-tag,.section-label { background: #f4f6fa; padding: 4px 12px; border-radius: 20px; font-size: 12px; color: var(--muted); }
h3 { font-size: 21px; line-height: 1.5; }
.card-desc { margin: 10px 0 20px; color: var(--muted); flex: 1; }
.package-meta { display: flex; justify-content: space-between; flex-wrap: wrap; gap: 8px; font-size: 14px; color: var(--muted); padding-bottom: 18px; }
.package-meta span { font-variant-numeric: tabular-nums; color: var(--ink); font-weight: 600; }
.button { min-height: 48px; padding: 10px 18px; display: inline-flex; align-items: center; justify-content: center; gap: 8px; border: 1px solid transparent; border-radius: 12px; text-decoration: none; font-weight: 650; text-align: center; transition: background .18s, border-color .18s, box-shadow .18s; }
.primary { background: var(--blue); color: white; }
.primary:hover { background: var(--blue-hover); }
.secondary { background: var(--surface); border-color: #c7d6e9; color: var(--blue); }
.secondary:hover { background: var(--soft); border-color: #91b1dc; }
.button:active { box-shadow: inset 0 2px 4px #10264025; }
.button:disabled { opacity: .65; cursor: wait; }
.button .ui-svg-icon { width: 20px; height: 20px; }
.card-footnote { margin-top: 14px; font-size: 13px; text-align: center; color: var(--muted); }
#cloud-downloads { margin-top: 40px; }
.section-description { color: var(--muted); margin: -8px 0 20px; }
.cloud-card { display: flex; align-items: center; gap: 16px; justify-content: space-between; border: 1px solid var(--line); border-radius: 16px; padding: 22px; background: var(--surface); }
.cloud-info { display: flex; align-items: center; gap: 14px; min-width: 0; }
.cloud-info h3 { font-size: 18px; }
.cloud-info p { font-size: 13px; color: var(--muted); }
.cloud-icon { width: 42px; height: 42px; flex-shrink: 0; border-radius: 12px; background: var(--soft); display: grid; place-items: center; color: var(--blue); }
.cloud-icon .ui-svg-icon { width: 24px; height: 24px; }
.cloud-card .button { font-size: 14px; flex-shrink: 0; }
.access-code { font-family: ui-monospace, Consolas, monospace; color: var(--ink); letter-spacing: .06em; user-select: all; }
.section-note { margin-top: 14px; color: var(--muted); font-size: 14px; }
.update-check { display: flex; align-items: center; gap: 18px; margin-top: 32px; padding: 24px; border-radius: 16px; background: #edf2f8; }
.update-icon { width: 26px; height: 26px; flex-shrink: 0; color: var(--blue); }
.update-copy { flex: 1; min-width: 0; }
.update-copy h2 { font-size: 17px; margin-bottom: 4px; }
.update-copy p { font-size: 14px; color: var(--muted); }
.update-check .button { flex-shrink: 0; }
.guide-section { margin-top: 44px; }
.text-link { font-size: 14px; text-decoration: none; min-height: 44px; display: inline-flex; align-items: center; }
.guide-switch { display: inline-flex; gap: 8px; background: #e9eef5; padding: 5px; border-radius: 13px; margin-bottom: 20px; }
.tab-btn { min-height: 44px; padding: 8px 24px; color: var(--muted); background: transparent; border: 0; border-radius: 9px; font-size: 15px; font-weight: 650; }
.tab-btn.active { color: var(--blue); background: white; box-shadow: 0 2px 5px #233b6110; }
.steps { display: grid; grid-template-columns: repeat(3,minmax(0,1fr)); gap: 24px; list-style: none; padding: 0; margin: 0; counter-reset: step; }
.steps li { counter-increment: step; border-top: 1px solid #ced9e7; padding-top: 18px; }
.steps li::before { content: "0" counter(step); color: #4d719f; font-size: 14px; font-weight: 700; display: block; margin-bottom: 10px; }
.steps h3 { font-size: 16px; margin-bottom: 8px; }
.steps p { color: var(--muted); font-size: 14px; }
.help-note { margin-top: 36px; padding: 18px 22px; border-left: 3px solid #b0c7e5; background: #eff3f8; font-size: 14px; color: var(--muted); }
.help-note strong { color: var(--ink); }
.help-note p { margin-top: 4px; }
footer { display: flex; justify-content: space-between; gap: 16px; max-width: 1080px; margin: auto; padding: 24px 0 max(24px, env(safe-area-inset-bottom)); border-top: 1px solid var(--line); font-size: 14px; color: var(--muted); }
footer a { text-decoration: none; color: var(--ink); font-weight: 750; }
.client-update-overlay { position: fixed; inset: 0; z-index: 30; display: none; align-items: center; justify-content: center; padding: 24px; background: #192d4b80; }
.client-update-overlay.show { display: flex; }
.client-update-modal { width: min(100%,440px); max-height: calc(100dvh - 48px); overflow-y: auto; padding: 32px; border-radius: 22px; background: white; box-shadow: 0 16px 60px #182d4a30; }
.modal-icon { width: 32px; height: 32px; color: var(--blue); margin-bottom: 14px; }
.client-update-modal h2 { font-size: 22px; }
.client-update-modal p { margin: 12px 0 24px; color: var(--muted); overflow-wrap: anywhere; }
.client-update-actions { display: grid; gap: 12px; }
@media(max-width:1150px) { .shell,footer { margin-left: 24px; margin-right: 24px; } }
@media(max-width:900px) { .cloud-card { flex-wrap: wrap; } .cloud-card .button { width: 100%; } }
@media(max-width:640px) {
  .topbar { position: relative; padding: max(12px,env(safe-area-inset-top)) 16px 12px; gap: 8px; flex-wrap: wrap; }
  .brand { font-size: 19px; } .brand span { display: none; }
  .topbar nav { gap: 0; } .topbar nav a { font-size: 14px; padding: 8px 10px; }
  .shell { margin: 0; padding: 20px max(16px,env(safe-area-inset-left)) 36px; }
  .intro { padding: 24px; margin-bottom: 30px; border-radius: 20px; }
  .intro-art { display: none; } .intro-links { gap: 16px; margin-top: 14px; font-size: 14px; }
  .section-heading { flex-wrap: wrap; gap: 8px; margin-bottom: 16px; }
  h2 { font-size: 22px; }
  .platform-grid,.cloud-grid { grid-template-columns: minmax(0,1fr); gap: 16px; }
  .platform-card { padding: 24px; }
  .cloud-card { padding: 20px; }
  .cloud-card .button { width: auto; }
  .section-description,.steps p,.help-note { font-size: 16px; }
  .update-check { padding: 20px; flex-wrap: wrap; gap: 12px; }
  .update-icon { display: none; } .update-copy { flex-basis: 100%; }
  .update-check .button { width: 100%; }
  .steps { grid-template-columns: minmax(0,1fr); gap: 20px; }
  .guide-section,#cloud-downloads { margin-top: 32px; }
  footer { margin: 0 16px; flex-wrap: wrap; }
}
@media(max-width:380px) { .cloud-card .button { width: 100%; } .intro { padding: 22px; } }
@media(prefers-reduced-motion:reduce) { html { scroll-behavior: auto; } .button { transition: none; } }