:root{
  --c-bg:#E4EDF6;--c-panel:#F6F9FD;--c-panel-2:#D6E2EF;--c-border:#C9D6E6;
  --c-accent:#2C8C6A;--c-accent-dark:#1E6650;--c-accent-glow:#3FA47F;--c-accent-soft:#D5ECE1;
  --c-ink:#22324A;--c-ink-dark:#172438;--c-ink-soft:#DCE5F0;--c-text:#1B2638;--c-muted:#5A6A80;
  --c-success:#2E9E5B;--c-warn:#C98A1B;--c-error:#C8453A;
  --c-hero-top:#EEF3FA;--c-hero-bottom:#DCE7F2;--c-white:#FFFFFF;
  --c-accent-05:rgba(44,140,106,.05);--c-accent-06:rgba(44,140,106,.06);--c-accent-10:rgba(44,140,106,.10);
  --c-accent-14:rgba(44,140,106,.14);--c-accent-24:rgba(44,140,106,.24);--c-accent-40:rgba(44,140,106,.40);
  --c-ink-06:rgba(34,50,74,.06);--c-ink-10:rgba(34,50,74,.10);--c-ink-16:rgba(34,50,74,.16);--c-ink-24:rgba(34,50,74,.24);
  --c-border-60:rgba(201,214,230,.6);--c-hl:rgba(255,255,255,.92);--c-hl-soft:rgba(255,255,255,.6);
  --c-gloss:rgba(255,255,255,.2);--c-header:rgba(246,249,253,.8);--c-clear:transparent;
  --flag-red:#D52B3C;--flag-white:#FFFFFF;--flag-blue:#263C82;--flag-black:#23262C;--flag-gold:#F1C232;
  --r-xs:6px;--r:10px;--r-pill:999px;--r-circle:50%;
  --f-display:'Inter','Noto Sans SC','PingFang SC','Microsoft YaHei',system-ui,sans-serif;
  --f-body:'Inter','Noto Sans SC','PingFang SC','Hiragino Sans','Microsoft YaHei',system-ui,sans-serif;
  --f-mono:'JetBrains Mono',ui-monospace,'SFMono-Regular',Menlo,Consolas,monospace;
  --weight-normal:400;--weight-medium:500;--weight-strong:600;
  --text-small:13px;--text-body:15px;--text-lead:20px;--text-h1:64px;--text-h2:36px;--text-h3:22px;
  --gutter:32px;--header-height:60px;--toc-height:64px;--anchor-offset:144px;
  --space-section:96px;--ease: .2s ease;
  --sh-card:0 1px 2px var(--c-ink-06),0 30px 72px -20px var(--c-accent-14),inset 0 1px 0 var(--c-hl),inset 0 0 0 1px var(--c-hl-soft);
  --sh-float:0 1px 2px var(--c-ink-06),0 14px 28px -12px var(--c-accent-24);
  --sh-float-ink:0 1px 2px var(--c-ink-06),0 14px 28px -12px var(--c-ink-24);
  --sh-btn:0 12px 24px -12px var(--c-accent-40),inset 0 1px 0 var(--c-gloss);
  --sh-btn-ink:0 12px 24px -12px var(--c-ink-24),inset 0 1px 0 var(--c-gloss);
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-padding-top:76px;scroll-behavior:smooth}
body{margin:0;background:var(--c-bg);color:var(--c-text);font-family:var(--f-body);font-size:var(--text-body);line-height:1.6;-webkit-font-smoothing:antialiased}
a{color:inherit;text-decoration:none}
button,input,select,textarea{font:inherit;color:inherit}
button{cursor:pointer}
button,a{-webkit-tap-highlight-color:var(--c-accent-14)}
button{border:0}
img{max-width:100%;height:auto}
svg{flex-shrink:0}
h1,h2,h3{font-family:var(--f-display);font-weight:var(--weight-normal);text-wrap:balance;overflow-wrap:break-word}
h1{font-size:clamp(52px,4.45vw,72px);line-height:1.12;letter-spacing:-.02em}
h2{font-size:var(--text-h2);line-height:1.3;margin:0 0 24px}
h3{font-size:var(--text-h3);line-height:1.4;margin:0 0 12px}
p{margin:0 0 20px}
strong,b{font-weight:var(--weight-strong)}
ul,ol{padding-left:24px}
code{font-family:var(--f-mono);overflow-wrap:anywhere}
pre{max-width:100%;overflow-x:auto;padding:24px;background:var(--c-panel-2);border-radius:var(--r)}
pre code{overflow-wrap:normal;white-space:pre}
:focus-visible{outline:2px solid var(--c-accent);outline-offset:2px}
[hidden]{display:none!important}
.no-break{white-space:nowrap}
.wrap{width:100%;max-width:1244px;margin-inline:auto;padding-inline:var(--gutter)}
.section{padding-top:var(--space-section);padding-bottom:var(--space-section)}
.section--compact{padding-top:48px;padding-bottom:48px}
.grid-two{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:32px}
.grid-three{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:24px}
.grid-two>*,.grid-three>*,.wrap>*{min-width:0}
.panel,.card{padding:32px;background:var(--c-panel);border:1px solid var(--c-border-60);border-radius:var(--r);box-shadow:var(--sh-card)}
.panel--inset{background:var(--c-panel-2);box-shadow:inset 0 1px 0 var(--c-hl-soft)}
.muted{color:var(--c-muted)}
.mono{font-family:var(--f-mono);font-variant-numeric:tabular-nums}
.eyebrow{font-family:var(--f-mono);font-size:var(--text-small);color:var(--c-accent-dark);letter-spacing:.08em}
.text-link{display:inline-flex;align-items:center;gap:6px;min-height:24px;color:var(--c-accent-dark)}
.text-link:hover{text-decoration:underline}
.prose{max-width:800px;line-height:1.85;overflow-wrap:anywhere}
.prose h2{margin-top:56px}
.prose h3{margin-top:32px}
.prose a{text-decoration:underline;text-underline-offset:3px;color:var(--c-accent-dark)}
.prose li+li{margin-top:8px}
.btn{
  display:inline-flex;align-items:center;justify-content:center;gap:8px;height:46px;padding:0 30px;
  border-radius:var(--r);font-size:16px;font-weight:var(--weight-medium);letter-spacing:.01em;
  border:1px solid var(--c-clear);flex-shrink:0;white-space:nowrap;transition:background-color var(--ease),transform var(--ease);
}
.btn:hover{transform:translateY(-1px)}
.btn--primary,.btn-primary{background:var(--c-accent);color:var(--c-white);box-shadow:var(--sh-btn)}
.btn--primary:hover,.btn-primary:hover{background:var(--c-accent-dark)}
.btn--ink,.btn-secondary{background:var(--c-ink);color:var(--c-white);box-shadow:var(--sh-btn-ink)}
.btn--ink:hover,.btn-secondary:hover{background:var(--c-ink-dark)}
.btn--outline{background:var(--c-clear);border-color:var(--c-border);color:var(--c-ink)}
.btn--outline:hover{background:var(--c-panel-2)}
.btn:active{transform:translateY(0)}
.btn:disabled,.btn[aria-disabled="true"]{opacity:.55;cursor:not-allowed;transform:none;pointer-events:none}
.btn svg{width:16px;height:16px}
.reveal{transition:opacity .35s ease,transform .35s ease}
.reveal.pending{opacity:0;transform:translateY(16px)}
.reveal.shown{opacity:1;transform:none}
#server-status{position:relative;display:block;min-height:160px;max-width:100%;overflow:hidden;margin-block:32px}
#server-status+*{margin-top:32px}
#server-status>*{min-width:0;max-width:100%}
.decorated{position:relative;overflow-x:clip;max-width:100%}

/* Shared navigation */
#site-header{position:sticky;top:0;z-index:50}
.topbar{position:sticky;top:0;z-index:50;background:var(--c-header);border-bottom:1px solid var(--c-ink-06);-webkit-backdrop-filter:saturate(1.4) blur(14px);backdrop-filter:saturate(1.4) blur(14px)}
.topbar__inner{width:min(1240px,100% - 48px);height:var(--header-height);margin:0 auto;display:flex;align-items:center;gap:32px;flex-wrap:nowrap}
.brand{display:inline-flex;align-items:center;gap:10px;flex:none;min-height:32px}
.brand__mark{display:block;width:32px;height:32px;filter:drop-shadow(0 6px 10px var(--c-accent-24))}
.brand__en{font-family:var(--f-display);font-size:19px;font-weight:var(--weight-strong);letter-spacing:-.01em;color:var(--c-ink);white-space:nowrap}
.brand__zh{font-size:13px;font-weight:var(--weight-normal);color:var(--c-muted);padding-left:10px;border-left:1px solid var(--c-border);line-height:1}
.mainnav{flex:1;min-width:0}
.mainnav__list{display:flex;align-items:center;list-style:none;margin:0;padding:0;gap:4px}
.mainnav__link{position:relative;display:inline-flex;align-items:center;gap:4px;height:36px;padding:0 12px;border-radius:var(--r-xs);font-size:15px;white-space:nowrap;color:var(--c-muted);background:none;border:0;cursor:pointer;transition:color var(--ease),background-color var(--ease)}
.mainnav__link:hover{color:var(--c-ink);background:var(--c-ink-06)}
.mainnav__link.is-current{color:var(--c-ink);font-weight:var(--weight-medium)}
.mainnav__link.is-current::after{content:"";position:absolute;left:50%;bottom:2px;width:4px;height:4px;margin-left:-2px;border-radius:var(--r-circle);background:var(--c-accent)}
.mainnav__caret{width:12px;height:12px;flex:none}
.mainnav__more{position:relative}
.mainnav__drop{position:absolute;top:calc(100% + 10px);left:0;min-width:248px;display:grid;grid-template-columns:1fr 1fr;gap:4px 12px;padding:14px;border-radius:var(--r);background:var(--c-panel);border:1px solid var(--c-border-60);box-shadow:var(--sh-float-ink);z-index:55}
.mainnav__group-title{display:block;margin:0 0 4px;padding:0 8px;font-family:var(--f-mono);font-size:11px;letter-spacing:.12em;color:var(--c-muted)}
.mainnav__drop a{display:flex;align-items:center;min-height:36px;padding:6px 8px;border-radius:var(--r-xs);font-size:14px;color:var(--c-text);white-space:nowrap}
.mainnav__drop a:hover,.mainnav__drop a.is-current{background:var(--c-accent-10);color:var(--c-accent-dark)}
.topbar__tools{display:flex;align-items:center;gap:12px;flex-shrink:0}
.langbox{position:relative}
.langswitch{display:inline-flex;align-items:center;justify-content:center;gap:6px;width:auto;min-width:44px;height:36px;padding:0 10px;border:0;border-radius:var(--r-xs);background:none;cursor:pointer;font-size:14px;color:var(--c-muted);white-space:nowrap}
.langswitch span{white-space:nowrap}
.langswitch:hover{background:var(--c-ink-06);color:var(--c-ink)}
.langswitch svg{width:16px;height:16px;flex:none}
.langpanel{position:absolute;right:0;top:calc(100% + 10px);z-index:60;min-width:180px;padding:8px;border:1px solid var(--c-border);border-radius:var(--r);background:var(--c-panel);box-shadow:var(--sh-float-ink)}
.langpanel a{display:flex;align-items:center;min-height:40px;padding:8px 12px;border-radius:var(--r-xs)}
.langpanel a:hover,.langpanel a[aria-current]{background:var(--c-accent-10);color:var(--c-accent-dark)}
.loginbtn{display:inline-flex;align-items:center;justify-content:center;gap:6px;height:36px;padding:0 16px;border-radius:var(--r);background:var(--c-ink);color:var(--c-white);font-size:14px;font-weight:var(--weight-medium);white-space:nowrap;box-shadow:var(--sh-btn-ink);transition:background-color var(--ease)}
.loginbtn:hover{background:var(--c-ink-dark)}
.loginbtn svg{width:15px;height:15px;flex:none}
.menu-toggle{display:none;align-items:center;justify-content:center;flex-direction:column;gap:4px;min-width:44px;min-height:44px;background:var(--c-clear);color:var(--c-ink);border-radius:var(--r-xs)}
.menu-toggle__line{display:block;width:20px;height:2px;background:currentColor}
.mobile-drawer{position:fixed;top:var(--header-height);right:0;left:0;height:calc(100dvh - var(--header-height));max-height:calc(100dvh - var(--header-height));overflow-y:auto;overscroll-behavior:contain;background:var(--c-panel);padding:20px var(--gutter) 40px;z-index:48}
.mobile-drawer a{display:flex;align-items:center;width:100%;min-height:44px;padding:12px 16px;border-radius:var(--r-xs)}
.mobile-drawer a:hover,.mobile-drawer a.is-current,.mobile-drawer a[aria-current]{background:var(--c-accent-10);color:var(--c-accent-dark)}
.mobile-drawer__languages{border-top:1px solid var(--c-border);margin-top:16px;padding-top:16px}
.menu-veil{position:fixed;inset:var(--header-height) 0 0;background:var(--c-ink-24);z-index:47}
html.nav-open{overflow:hidden}

/* Shared footer */
.site-footer{background:var(--c-panel-2);border-top:1px solid var(--c-border);padding-top:56px;padding-bottom:24px}
.footer-grid{display:grid;grid-template-columns:1.3fr 1fr 1fr;gap:48px}
.footer-brand p{max-width:340px;margin:20px 0;color:var(--c-muted)}
.footer-title{font-size:16px;font-weight:var(--weight-medium);margin:0 0 12px}
.footer-links{list-style:none;margin:0;padding:0;display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:6px 16px}
.footer-links a,.footer-languages a,.footer-legal a{display:inline-flex;align-items:center;min-height:28px;color:var(--c-ink)}
.footer-links a:hover,.footer-languages a:hover,.footer-legal a:hover{color:var(--c-accent-dark);text-decoration:underline}
.footer-languages{display:flex;flex-wrap:wrap;gap:8px 24px;margin-top:32px;padding-top:24px;border-top:1px solid var(--c-border)}
.footer-bottom{display:flex;justify-content:space-between;flex-wrap:wrap;gap:16px;margin-top:24px;color:var(--c-muted);font-size:13px}
.footer-legal{display:flex;flex-wrap:wrap;gap:20px}

@media(max-width:1180px){
  .mainnav__link{padding-inline:9px}
  .topbar__inner{gap:20px}
  .brand__zh{display:none}
}
@media(max-width:1000px){
  .mainnav{display:none}
  .menu-toggle{display:inline-flex}
  .topbar__tools{margin-left:auto}
}
@media(min-width:1001px){.mobile-drawer,.menu-veil{display:none!important}}
@media(max-width:768px){
  :root{--gutter:20px;--space-section:64px;--text-h2:28px;--text-h3:20px}
  h1{font-size:38px;line-height:1.18}
  .grid-two,.grid-three,.footer-grid{grid-template-columns:minmax(0,1fr)}
  .footer-grid{gap:32px}
  .panel,.card{padding:24px}
}
@media(max-width:640px){
  :root{--gutter:16px}
  .no-break{white-space:normal}
  .tilt,.float-refund,.float-noemail{transform:none}
  .decorated{max-width:100%;overflow-x:clip}
  .topbar__inner{width:calc(100% - 32px);gap:8px}
  .topbar__tools{gap:4px;margin-left:auto}
  .brand{gap:6px}
  .brand__en{font-size:16px}
  .brand__mark{width:28px;height:28px}
  .langswitch{padding-inline:5px;font-size:12px}
  .langswitch svg{display:none}
  .loginbtn{padding-inline:10px;font-size:13px}
  .loginbtn svg{display:none}
  .footer-links{gap:8px}
}
@media(max-width:359px){
  .brand__en{font-size:14px}
  .brand__mark{width:24px;height:24px}
  .langswitch{font-size:11px;padding-inline:3px}
  .topbar__tools{gap:2px}
  .loginbtn{padding-inline:8px}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{transition:none!important;animation:none!important}
  .reveal,.reveal.pending,.reveal.shown{opacity:1;transform:none}
  .btn:hover{transform:none}
}