:root {
  color-scheme: light;
  --bg: #FBFBFD;
  --panel: #FFFFFF;
  --panel-2: #EEF3FB;
  --panel-soft: #F6F8FC;
  --border: #DDE4EF;
  --border-soft: #E7ECF4;
  --accent: #1A66F0;
  --accent-2: #5AA2FF;
  --accent-lift: #3B80F5;
  --accent-deep: #1355CC;
  --accent-tint: #E3EDFE;
  --accent-tint-2: #D4E4FE;
  --accent-line: rgba(26,102,240,.48);
  --navy: #0B2F63;
  --navy-2: #173F7A;
  --text: #0E2747;
  --muted: #5B6B82;
  --faint: #9AA7BA;
  --success: #12A36B;
  --success-tint: #DCF3E9;
  --warn: #D99A00;
  --error: #D93B3B;
  --magenta: #D64CF2;
  --magenta-2: #E58CF8;
  --on-dark: #FFFFFF;
  --flag-red: #D52B2F;
  --flag-blue: #1F3E8C;
  --flag-white: #FFFFFF;
  --glass: rgba(255,255,255,.56);
  --glass-edge: rgba(255,255,255,.88);
  --hl: rgba(255,255,255,.95);
  --hl-soft: rgba(255,255,255,.35);
  --atmo-top: rgba(26,102,240,.06);
  --atmo-mid: rgba(26,102,240,.025);
  --atmo-end: rgba(251,251,253,0);
  --veil: rgba(11,47,99,.24);
  --clear: transparent;
  --shadow-window: 0 40px 80px -24px rgba(26,102,240,.18),0 12px 48px rgba(26,102,240,.12),0 2px 6px rgba(11,47,99,.06);
  --shadow-float: 0 16px 48px rgba(26,102,240,.12),0 4px 12px rgba(11,47,99,.08);
  --shadow-sheet: 0 8px 32px rgba(26,102,240,.10);
  --shadow-chip: 0 6px 18px -8px rgba(26,102,240,.22);
  --shadow-cta: 0 12px 28px -10px rgba(26,102,240,.55);
  --shadow-cta-navy: 0 12px 28px -12px rgba(11,47,99,.55);
  --shadow-mark: 0 6px 14px -4px rgba(26,102,240,.45);
  --shadow-pick: 0 8px 18px -6px rgba(11,47,99,.55);
  --shadow-connect: 0 8px 18px -6px rgba(26,102,240,.6);
  --font-display: "Inter","Noto Sans SC","PingFang SC","Hiragino Sans","Apple SD Gothic Neo","Microsoft YaHei",system-ui,sans-serif;
  --font-body: "Inter","Noto Sans SC","PingFang SC","Hiragino Sans","Malgun Gothic","Microsoft YaHei",system-ui,-apple-system,sans-serif;
  --font-mono: "JetBrains Mono",ui-monospace,"SFMono-Regular",Menlo,Consolas,monospace;
  --text-xs: 11px;
  --text-small: 12px;
  --text-caption: 12.5px;
  --text-label: 13px;
  --text-label-lg: 13.5px;
  --text-sm: 14px;
  --text-alt: 14.5px;
  --text-nav: 15px;
  --text-body: 16px;
  --text-lede: 17px;
  --text-lg: 18px;
  --text-brand: 20px;
  --text-subtitle: 22px;
  --text-card: 24px;
  --text-h3: 28px;
  --text-h2: clamp(28px,3.4vw,44px);
  --text-h1: clamp(52px,5vw,68px);
  --text-hero: 68px;
  --text-hero-mobile: 38px;
  --text-price: 40px;
  --weight-normal: 400;
  --weight-medium: 500;
  --weight-semibold: 600;
  --weight-bold: 700;
  --weight-heavy: 800;
  --r-xs: 6px;
  --r-sm: 10px;
  --r-md: 14px;
  --r-lg: 18px;
  --r-window: 24px;
  --r-board: 28px;
  --r-pill: 999px;
  --r-circle: 50%;
  --gutter: 40px;
  --wrap-width: 1280px;
  --reading-width: 840px;
  --section-space: 80px;
  --header-height: 68px;
  --header-edge: 112px;
  --anchor-offset: 96px;
  --toc-offset: 88px;
  --toc-landing: 168px;
  --ease: cubic-bezier(.2,.65,.3,1);
  --fast: .2s;
  --reveal-duration: .35s;
}
*,*::before,*::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; scroll-padding-top: var(--anchor-offset); }
body { margin: 0; background: var(--bg); color: var(--text); font-family: var(--font-body); font-size: var(--text-body); line-height: 1.6; -webkit-font-smoothing: antialiased; }
html.nav-open { overflow: hidden; }
[hidden] { display: none !important; }
a { color: inherit; text-decoration: none; }
button,input,select,textarea { font: inherit; }
button { cursor: pointer; color: inherit; }
button:disabled { cursor: not-allowed; }
button,summary,a { -webkit-tap-highlight-color: var(--accent-tint); }
:where(a,button,input,select,textarea,summary,[tabindex]):focus-visible { outline: 2px solid var(--accent); outline-offset: 4px; }
img { display: block; max-width: 100%; height: auto; }
svg { display: block; flex-shrink: 0; }
figure,p { margin: 0; }
ul,ol { padding-left: 1.4em; }
h1,h2,h3,h4 { font-family: var(--font-display); color: var(--navy); font-weight: var(--weight-heavy); overflow-wrap: break-word; text-wrap: balance; }
h1 { margin: 0 0 24px; font-size: var(--text-h1); line-height: 1.12; letter-spacing: -.02em; }
h2 { margin: 0 0 24px; font-size: var(--text-h2); line-height: 1.2; letter-spacing: -.02em; }
h3 { margin: 0 0 16px; font-size: var(--text-h3); line-height: 1.3; letter-spacing: -.01em; }
h4 { font-size: var(--text-lg); }
p + p { margin-top: 16px; }
code { font-family: var(--font-mono); overflow-wrap: anywhere; }
pre { max-width: 100%; overflow-x: auto; padding: 20px; border: 1px solid var(--border); border-radius: var(--r-md); background: var(--panel-2); }
pre code { overflow-wrap: normal; white-space: pre; font-size: var(--text-sm); }
table { border-collapse: collapse; }
th,td { text-align: left; }
section[id] { scroll-margin-top: var(--anchor-offset); }
.wrap,.vb-wrap { width: 100%; max-width: var(--wrap-width); margin-inline: auto; padding-inline: var(--gutter); }
.reading-wrap { width: 100%; max-width: var(--reading-width); margin-inline: auto; padding-inline: var(--gutter); }
.sec { padding-top: var(--section-space); padding-bottom: var(--section-space); }
.grid { display: grid; gap: 24px; }
.grid > *,.vb-hero-grid > *, .footer-grid > * { min-width: 0; }
.grid-three { grid-template-columns: repeat(3,minmax(0,1fr)); }
.grid-five { grid-template-columns: repeat(5,minmax(0,1fr)); }
.row { display: flex; align-items: center; flex-wrap: wrap; gap: 12px; }
.stack { display: grid; gap: 24px; }
.center { text-align: center; }
.muted { color: var(--muted); }
.num { font-family: var(--font-mono); font-weight: var(--weight-semibold); letter-spacing: -.01em; font-variant-numeric: tabular-nums; }
.no-break { white-space: nowrap; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip-path: inset(50%); white-space: nowrap; border: 0; }
.text-link { color: var(--accent); text-decoration: underline; text-underline-offset: 4px; }
.text-link:hover { color: var(--accent-deep); }
.btn { display: inline-flex; align-items: center; justify-content: center; gap: 10px; min-height: 48px; padding: 11px 24px; border: 1px solid var(--clear); border-radius: var(--r-pill); font-size: var(--text-body); font-weight: var(--weight-bold); line-height: 1.5; text-align: center; transition: background-color var(--fast),box-shadow var(--fast),transform var(--fast); }
.btn svg { width: 20px; height: 20px; }
.btn-primary { background: var(--accent); color: var(--on-dark); box-shadow: var(--shadow-cta); }
.btn-primary:hover,.btn-primary.is-hover { background: var(--accent-deep); transform: translateY(-1px); }
.btn-secondary { background: var(--navy); color: var(--on-dark); box-shadow: var(--shadow-cta-navy); }
.btn-secondary:hover { background: var(--navy-2); }
.btn-outline { background: var(--panel); color: var(--navy); border-color: var(--navy); }
.btn-outline:hover { background: var(--accent-tint); }
.btn:active,.btn.is-active { transform: translateY(1px); box-shadow: none; }
.btn:disabled,.btn[aria-disabled="true"] { background: var(--panel-2); color: var(--muted); border-color: var(--border); box-shadow: none; transform: none; }
.panel { padding: 28px; border: 1px solid var(--border-soft); border-radius: var(--r-window); background: var(--panel); box-shadow: var(--shadow-sheet),inset 0 0 0 1px var(--hl); }
.prose { min-width: 0; overflow-wrap: anywhere; }
.prose p,.prose li { line-height: 1.85; }
.prose h2 { margin-top: 56px; }
.prose h3 { margin-top: 32px; }
.prose a { color: var(--accent); text-decoration: underline; text-underline-offset: 3px; }
.prose li + li { margin-top: 8px; }
.reveal { transition: opacity var(--reveal-duration) var(--ease),transform var(--reveal-duration) var(--ease); }
.reveal.pending { opacity: 0; transform: translateY(16px); }
.reveal.shown { opacity: 1; transform: none; }
.decorated-section { position: relative; overflow-x: clip; max-width: 100%; }
#server-status { position: relative; display: block; min-width: 0; width: 100%; max-width: 100%; overflow: hidden; margin-top: 24px; margin-bottom: 32px; }
#server-status + * { margin-top: 24px; }

/* Announcement and shared header */
.vb-notice { position: relative; background: var(--navy); color: var(--on-dark); }
.vb-notice-inner { min-height: 44px; display: flex; align-items: center; justify-content: center; gap: 20px; padding: 6px 64px; font-size: var(--text-sm); }
.vb-notice-text { letter-spacing: .02em; }
.vb-notice-short { display: none; }
.vb-notice-pill { display: inline-flex; align-items: center; justify-content: center; gap: 6px; min-height: 30px; padding: 0 14px; border-radius: var(--r-pill); background: var(--accent-tint-2); color: var(--navy); font-size: var(--text-label); font-weight: var(--weight-bold); white-space: nowrap; }
.vb-notice-pill:hover { background: var(--panel); }
.vb-notice-close { position: absolute; right: 20px; top: 50%; width: 32px; height: 32px; margin-top: -16px; padding: 0; display: grid; place-items: center; border: 0; border-radius: var(--r-circle); background: var(--clear); color: var(--on-dark); cursor: pointer; }
.vb-notice-close:hover { background: var(--navy-2); }
.vb-notice-close svg { width: 16px; height: 16px; }
.vb-notice-switch { position: absolute; width: 1px; height: 1px; opacity: 0; }
.vb-notice-switch:checked + .vb-notice { display: none; }
.vb-notice-switch:focus-visible + .vb-notice .vb-notice-close { outline: 2px solid var(--accent-2); outline-offset: 2px; }
#site-header { position: relative; z-index: 50; }
.vb-bar { position: relative; z-index: 53; background: var(--panel); border-bottom: 1px solid var(--border); }
.vb-bar-inner { display: flex; align-items: center; flex-wrap: nowrap; gap: 24px; min-height: var(--header-height); }
.vb-brand { display: inline-flex; align-items: center; gap: 10px; font-family: var(--font-display); font-size: var(--text-brand); font-weight: var(--weight-heavy); letter-spacing: -.02em; color: var(--navy); flex-shrink: 0; white-space: nowrap; }
.vb-logo { width: 34px; height: 34px; flex-shrink: 0; }
.vb-brand-zh { color: var(--muted); font-weight: var(--weight-medium); }
.vb-nav { flex: 1; min-width: 0; }
.vb-nav ul { display: flex; align-items: center; list-style: none; margin: 0; padding: 0; }
.vb-nav li { display: flex; align-items: center; white-space: nowrap; }
.vb-nav li + li::before { content: "·"; margin: 0 8px; color: var(--faint); font-weight: var(--weight-bold); }
.vb-nav a { position: relative; padding: 6px 0; font-size: var(--text-nav); font-weight: var(--weight-medium); color: var(--text); }
.vb-nav a:hover { color: var(--accent); }
.vb-nav-more { position: relative; }
.vb-nav-more > button { padding: 6px 0; border: 0; background: var(--clear); font-size: var(--text-nav); font-weight: var(--weight-medium); cursor: pointer; white-space: nowrap; }
.vb-nav-more > button::after { content: " ▾"; }
.vb-nav-more > button:hover { color: var(--accent); }
.vb-nav-more > .vb-lang-panel { min-width: 200px; }
.vb-nav-more a { display: flex; align-items: center; width: 100%; min-height: 44px; padding: 8px 12px; border-radius: var(--r-sm); }
.vb-nav-more a:hover { background: var(--accent-tint); }
.vb-nav a[aria-current="page"] { color: var(--navy); font-weight: var(--weight-bold); }
.vb-nav a[aria-current="page"]::after { content: ""; position: absolute; left: 50%; bottom: -3px; width: 5px; height: 5px; margin-left: -2.5px; border-radius: var(--r-circle); background: var(--accent); }
.vb-bar-tools { margin-left: auto; display: flex; align-items: center; gap: 18px; flex-shrink: 0; }
.vb-lang { position: relative; display: inline-flex; align-items: center; gap: 4px; font-size: var(--text-sm); color: var(--muted); white-space: nowrap; }
.vb-lang-button { display: inline-flex; align-items: center; justify-content: center; gap: 5px; width: auto; min-width: 32px; min-height: 40px; padding: 4px 0; border: 0; background: var(--clear); color: var(--muted); font-size: var(--text-sm); white-space: nowrap; }
.vb-lang-button span { white-space: nowrap; }
.vb-lang-button svg { width: 16px; height: 16px; }
.vb-lang-panel { position: absolute; z-index: 60; top: calc(100% + 10px); right: 0; min-width: 180px; padding: 8px; border: 1px solid var(--border); border-radius: var(--r-md); background: var(--panel); box-shadow: var(--shadow-float); }
.vb-lang-panel a { display: flex; align-items: center; min-height: 44px; padding: 8px 12px; border-radius: var(--r-sm); color: var(--text); }
.vb-lang-panel a:hover,.vb-lang-panel a[aria-current="true"] { background: var(--accent-tint); color: var(--navy); }
.vb-login { display: inline-flex; align-items: center; justify-content: center; min-height: 40px; padding: 0 22px; border: 1.5px solid var(--navy); border-radius: var(--r-pill); font-size: var(--text-nav); font-weight: var(--weight-bold); color: var(--navy); white-space: nowrap; }
.vb-login:hover { background: var(--navy); color: var(--on-dark); }
.vb-menu-button { display: none; align-items: center; justify-content: center; min-width: 44px; min-height: 44px; padding: 10px; border: 1px solid var(--border); border-radius: var(--r-sm); color: var(--navy); background: var(--panel); }
.vb-menu-button svg { width: 22px; height: 22px; }
.vb-menu-open-icon { display: block; }
.vb-menu-close-icon { display: none; }
.vb-menu-button[aria-expanded="true"] .vb-menu-open-icon { display: none; }
.vb-menu-button[aria-expanded="true"] .vb-menu-close-icon { display: block; }
.vb-drawer { position: fixed; z-index: 52; top: var(--header-edge); right: 0; left: 0; height: calc(100dvh - var(--header-edge)); max-height: calc(100dvh - var(--header-edge)); overflow-y: auto; overscroll-behavior: contain; padding: 16px var(--gutter) 32px; background: var(--panel); border-top: 1px solid var(--border); }
.vb-drawer ul { list-style: none; margin: 0; padding: 0; }
.vb-drawer a { display: flex; align-items: center; width: 100%; min-height: 48px; padding: 12px 14px; border-radius: var(--r-sm); }
.vb-drawer a:hover,.vb-drawer a[aria-current] { background: var(--accent-tint); color: var(--navy); }
.vb-drawer-title { margin: 20px 14px 6px; padding-top: 16px; border-top: 1px solid var(--border); font-size: var(--text-sm); color: var(--muted); }
.vb-veil { position: fixed; z-index: 51; top: var(--header-edge); right: 0; bottom: 0; left: 0; border: 0; background: var(--veil); }

/* Footer */
.site-footer { background: var(--panel-2); border-top: 1px solid var(--border); padding-top: 56px; padding-bottom: 28px; }
.footer-grid { display: grid; grid-template-columns: 1.35fr 1fr 1fr 1fr; gap: 40px; }
.footer-brand { max-width: 28em; }
.footer-brand p { margin-top: 18px; font-size: var(--text-sm); color: var(--muted); }
.footer-title { margin: 0 0 16px; color: var(--navy); font-size: var(--text-body); font-weight: var(--weight-bold); }
.footer-links { display: grid; gap: 4px; list-style: none; padding: 0; margin: 0; }
.footer-links a { display: inline-flex; align-items: center; min-height: 32px; padding-block: 4px; font-size: var(--text-sm); }
.footer-links a:hover { color: var(--accent); text-decoration: underline; text-underline-offset: 4px; }
.footer-bottom { display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 16px; margin-top: 40px; padding-top: 24px; border-top: 1px solid var(--border); font-size: var(--text-sm); color: var(--muted); }
.footer-legal { display: flex; flex-wrap: wrap; gap: 20px; }
.footer-legal a { display: inline-flex; align-items: center; min-height: 28px; }

@media (max-width: 1240px) {
  .vb-bar-inner { gap: 24px; }
  .vb-nav li + li::before { margin-inline: 8px; }
  .vb-bar-tools { gap: 12px; }
}
@media (max-width: 1180px) {
  .vb-nav { display: none; }
  .vb-menu-button { display: inline-flex; }
  .vb-bar-tools { margin-left: auto; }
}
@media (min-width: 1181px) {
  .vb-drawer,.vb-veil { display: none; }
  html.nav-open { overflow: auto; }
}
@media (max-width: 900px) {
  .grid-five { grid-template-columns: repeat(2,minmax(0,1fr)); }
  .footer-grid { grid-template-columns: repeat(2,minmax(0,1fr)); }
}
@media (max-width: 768px) {
  h1 { font-size: clamp(28px,6vw,40px); }
  .grid-three { grid-template-columns: minmax(0,1fr); }
}
@media (max-width: 640px) {
  :root { --gutter: 20px; --section-space: 48px; }
  .no-break { white-space: normal; }
  .tilt,.decorative-tilt { transform: none; }
  .decorated-section { max-width: 100%; }
  .vb-bar-inner { gap: 8px; }
  .vb-brand { gap: 7px; font-size: var(--text-body); }
  .vb-logo { width: 28px; height: 28px; }
  .vb-bar-tools { gap: 6px; margin-left: auto; }
  .vb-lang-button { min-width: 32px; }
  .vb-lang-button .vb-lang-name { display: none; }
  .vb-login { min-height: 36px; padding: 0 14px; font-size: var(--text-sm); }
  .vb-menu-button { padding: 8px; }
  .vb-notice-inner { padding: 6px 52px 6px 16px; gap: 12px; font-size: var(--text-label); justify-content: flex-start; }
  .vb-notice-long { display: none; }
  .vb-notice-short { display: inline; white-space: nowrap; }
  .vb-notice-pill { min-height: 28px; padding-inline: 10px; font-size: var(--text-small); }
  .vb-notice-close { right: 10px; }
  .footer-grid { grid-template-columns: minmax(0,1fr); gap: 28px; }
  .panel { padding: 20px; }
}
@media (max-width: 359px) {
  :root { --gutter: 16px; }
  .vb-brand { gap: 6px; font-size: var(--text-nav); }
  .vb-login { padding-inline: 12px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *,*::before,*::after { transition-duration: 0s !important; animation: none !important; }
  .reveal,.reveal.pending,.reveal.shown { opacity: 1; transform: none; }
}