:root{
  --bg:#E6EBF7;--bg-top:#EEF1FA;--bg-bottom:#E2E8F5;--panel:#F7F9FE;--panel-2:#D9E0F1;--white:#FFFFFF;
  --border:#C8D1E6;--border-soft:rgba(200,209,230,.7);
  --accent:#E2551C;--accent-dark:#B23E0C;--accent-14:rgba(226,85,28,.14);--accent-60:rgba(226,85,28,.6);--accent-on-dark:rgba(226,85,28,.14);
  --text:#141A2E;--muted:#566079;--muted-soft:#7B85A0;--success:#1E9467;--warn:#C98A0E;--error:#CF3548;
  --pink:#F07AA8;--sky:#56B7E2;--sky-line:rgba(86,183,226,.55);--sky-tint:rgba(86,183,226,.12);
  --blob-orange:#F6B08A;--blob-pink:#EFB6D6;--blob-sky:#A9DDF2;
  --halo-a:rgba(226,85,28,.18);--halo-b:rgba(240,122,168,.16);--halo-c:rgba(86,183,226,.18);
  --hl-white:rgba(255,255,255,.82);--glass:rgba(247,249,254,.74);--nav-glass:rgba(238,241,250,.74);--notice:#EEF0F6;--grid-line:rgba(20,26,46,.04);--q-btn:#E2E8F5;--mask-ink:#000000;
  --win:#121A30;--win-top:#18223E;--win-bar:rgba(255,255,255,.03);--win-line:rgba(255,255,255,.08);--win-cell:rgba(255,255,255,.045);--win-hl:rgba(255,255,255,.11);--win-glow:rgba(240,122,168,.13);
  --win-text:#E8ECF8;--win-muted:#8F9AB9;--ok-tint:rgba(30,148,103,.22);--ok-on-dark:#86DDB8;
  --flag-red:#C8202F;--flag-blue:#22397A;--flag-navy:#1B2D6B;--flag-white:#FFFFFF;--flag-edge:rgba(20,26,46,.14);--veil:rgba(20,26,46,.35);
  --shadow-soft:0 16px 40px rgba(226,85,28,.10);
  --shadow-chip:0 12px 28px -8px rgba(226,85,28,.22),0 2px 6px rgba(20,26,46,.06);
  --shadow-halo:0 34px 64px -26px rgba(226,85,28,.12),0 16px 40px rgba(226,85,28,.10);
  --shadow-q:0 10px 28px -12px rgba(226,85,28,.22),0 1px 2px rgba(20,26,46,.06);
  --shadow-win:0 18px 30px -18px rgba(18,26,48,.55);
  --shadow-win-strong:0 34px 50px -22px rgba(18,26,48,.62),0 16px 40px rgba(226,85,28,.10);
  --shadow-cta:0 12px 24px -12px rgba(226,85,28,.6);
  --r-btn:6px;--r-panel:10px;--r-halo:28px;--r-pill:999px;--r-small:8px;--r-flag:3px;--r-mobile-halo:20px;
  --font-display:"Inter","Noto Sans SC","PingFang SC","Hiragino Sans GB","Microsoft YaHei",system-ui,sans-serif;
  --font-body:"Inter","Noto Sans SC","PingFang SC","Microsoft YaHei",system-ui,-apple-system,"Segoe UI",sans-serif;
  --font-mono:"JetBrains Mono",ui-monospace,"SFMono-Regular",Menlo,Consolas,monospace;
  --gutter:24px;--content-max:1280px;--reading-max:860px;--bar-height:60px;--header-bottom:94px;--anchor-offset:110px;--toc-offset:172px;
  --size-display:68px;--size-section:40px;--size-body:16px;--size-small:14px;
  --weight-display:900;--weight-bold:700;--weight-body:400;
  --ease:ease;--speed:.2s;--section-space:80px;
}
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth;scroll-padding-top:var(--anchor-offset)}
body{margin:0;font-family:var(--font-body);font-size:var(--size-body);color:var(--text);background:var(--bg);line-height:1.5;-webkit-font-smoothing:antialiased}
img,svg{vertical-align:middle}
img{max-width:100%;height:auto}
svg{flex-shrink:0}
a{color:inherit;text-underline-offset:3px}
button,input,select,textarea{font:inherit;color:inherit}
button{cursor:pointer}
button,a,input,summary,select,textarea{-webkit-tap-highlight-color:var(--accent-14)}
:where(a,button,input,summary,select,textarea,[tabindex]):focus-visible{outline:2px solid var(--accent-dark);outline-offset:3px}
button:disabled{cursor:not-allowed}
[hidden]{display:none!important}
h1,h2,h3,h4{font-family:var(--font-display);color:var(--text);text-wrap:balance}
h1{font-size:clamp(52px,5vw,72px);line-height:1.1;font-weight:var(--weight-display);letter-spacing:-.02em}
h2{font-size:var(--size-section);line-height:1.2;font-weight:var(--weight-display);letter-spacing:-.02em}
h3{font-size:24px;line-height:1.3;font-weight:800}
p{margin:0 0 1.25em}
h1,h2,h3{overflow-wrap:break-word}
ul,ol{padding-left:1.5em}
code{font-family:var(--font-mono);overflow-wrap:anywhere}
pre{max-width:100%;overflow-x:auto;padding:20px;border-radius:var(--r-panel);background:var(--win);color:var(--win-text)}
pre code{overflow-wrap:normal;white-space:pre}
table{border-collapse:collapse}
th,td{text-align:left}
.no-break{white-space:nowrap}
.sr-only{position:absolute;width:1px;height:1px;padding:0;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
.shell,.wrap{width:100%;max-width:calc(var(--content-max) + 48px);margin-inline:auto;padding-inline:var(--gutter)}
.shell{max-width:1328px}
.reading-wrap{width:100%;max-width:calc(var(--reading-max) + 48px);padding-inline:var(--gutter);margin-inline:auto}
.section{padding-top:var(--section-space);padding-bottom:var(--section-space)}
.section--grid{background-image:linear-gradient(var(--grid-line) 1px,transparent 1px),linear-gradient(90deg,var(--grid-line) 1px,transparent 1px);background-size:32px 32px}
:where(.grid,.card-grid,.feature-row,.wins,.footer-grid)>*{min-width:0}
.panel,.card{min-width:0;padding:28px;border-radius:var(--r-panel);background:var(--panel);border:1px solid var(--border-soft);box-shadow:inset 0 1px 0 var(--hl-white),var(--shadow-soft)}
.card-grid{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));gap:24px}
.muted{color:var(--muted)}
.mono{font-family:var(--font-mono);font-variant-numeric:tabular-nums}
.kicker{font-family:var(--font-mono);font-size:12px;color:var(--muted);letter-spacing:.04em}
.text-link{display:inline-flex;align-items:center;gap:8px;min-height:24px;color:var(--accent-dark);font-weight:700}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;min-height:48px;padding:0 22px;border:0;border-radius:var(--r-btn);font:700 16px/1.2 var(--font-body);text-decoration:none;flex-shrink:0;white-space:nowrap;transition:background-color var(--speed) var(--ease),transform var(--speed) var(--ease),box-shadow var(--speed) var(--ease)}
.btn svg{width:16px;height:16px;flex:none}
.btn--primary,.btn-primary{background:var(--accent);color:var(--white);box-shadow:var(--shadow-cta)}
.btn--primary:hover,.btn-primary:hover{background:var(--accent-dark);transform:translateY(-1px)}
.btn--ghost{color:var(--text);background:var(--glass);box-shadow:inset 0 0 0 1.5px var(--text)}
.btn--ghost:hover{background:var(--panel)}
.btn--small{min-height:36px;padding-inline:16px;font-size:14px}
.btn:disabled,.btn[aria-disabled="true"]{background:var(--panel-2);color:var(--muted);box-shadow:none;transform:none}
.cta-row{display:flex;gap:12px;justify-content:center;margin-top:20px}
.notice{background:var(--notice);border-bottom:1px solid var(--border-soft);font-size:13px;color:var(--muted)}
.notice__row{display:flex;align-items:center;justify-content:center;gap:10px;min-height:34px}
.notice__dot{width:8px;height:8px;border-radius:var(--r-pill);flex:none;background:var(--accent);box-shadow:0 0 0 3px var(--accent-14)}
.notice__text{color:var(--text)}
.notice__link{display:inline-flex;align-items:center;gap:6px;min-height:24px;font-weight:600;color:var(--text);text-decoration:underline;text-decoration-thickness:1px}
.notice__link svg{width:14px;height:14px;transition:transform var(--speed) var(--ease)}
.notice__link:hover svg{transform:translateX(3px)}
#site-header{position:sticky;top:0;z-index:50;display:block}
.topbar{position:sticky;top:0;z-index:50;background:var(--nav-glass);backdrop-filter:blur(14px) saturate(1.2);-webkit-backdrop-filter:blur(14px) saturate(1.2);border-bottom:1px solid var(--border-soft)}
.topbar__row{display:flex;align-items:center;gap:24px;height:var(--bar-height);flex-wrap:nowrap}
.mark{display:flex;align-items:center;gap:10px;text-decoration:none;flex:none;min-height:32px}
.mark img{width:32px;height:32px;flex:none;border-radius:var(--r-small);box-shadow:var(--shadow-soft)}
.mark__en{font-family:var(--font-display);font-weight:800;font-size:18px;letter-spacing:-.02em;color:var(--text);white-space:nowrap}
.mark__zh{font-weight:500;font-size:15px;color:var(--muted);white-space:nowrap}
.mainnav{flex:1;min-width:0;display:flex;justify-content:center}
.mainnav ul{display:flex;align-items:center;gap:2px;list-style:none;margin:0;padding:0}
.mainnav a{display:flex;align-items:center;gap:6px;padding:7px 11px;min-height:32px;border-radius:var(--r-btn);font-size:14px;font-weight:500;color:var(--muted);text-decoration:none;white-space:nowrap;transition:background-color var(--speed),color var(--speed)}
.mainnav a svg{width:16px;height:16px;flex:none}
.mainnav a:hover{color:var(--text);background:var(--glass)}
.mainnav a[aria-current="page"]{color:var(--text);background:var(--panel);box-shadow:inset 0 0 0 1px var(--border)}
.topbar__tools{display:flex;align-items:center;gap:8px;flex-shrink:0;margin-left:auto}
.language{position:relative}
.lang{display:inline-flex;align-items:center;justify-content:center;gap:6px;min-height:36px;min-width:36px;width:auto;padding:0 10px;border:0;border-radius:var(--r-btn);background:transparent;font:500 14px/1 var(--font-body);color:var(--muted);cursor:pointer}
.lang span{white-space:nowrap}
.lang svg{width:16px;height:16px;flex:none}
.lang:hover{background:var(--glass);color:var(--text)}
.lang-panel{position:absolute;right:0;top:calc(100% + 10px);z-index:80;min-width:180px;padding:8px;border:1px solid var(--border);border-radius:var(--r-panel);background:var(--panel);box-shadow:var(--shadow-soft)}
.lang-panel a{display:flex;align-items:center;min-height:44px;padding:8px 12px;border-radius:var(--r-btn);text-decoration:none;color:var(--text)}
.lang-panel a:hover,.lang-panel a[aria-current="true"]{background:var(--panel-2)}
.login{display:inline-flex;align-items:center;justify-content:center;gap:6px;height:36px;padding:0 16px;border-radius:var(--r-btn);background:var(--text);color:var(--panel);font-size:14px;font-weight:600;text-decoration:none;white-space:nowrap;transition:background-color var(--speed)}
.login svg{width:15px;height:15px;flex:none}
.login:hover{background:var(--accent-dark)}
.menu-toggle{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-btn);background:var(--panel);color:var(--text)}
.menu-toggle svg{width:22px;height:22px}
.nav-drawer{position:fixed;z-index:70;top:var(--header-bottom);right:0;left:0;height:calc(100dvh - var(--header-bottom));max-height:calc(100dvh - var(--header-bottom));overflow-y:auto;overscroll-behavior:contain;background:var(--panel);padding:16px var(--gutter) 32px;border-top:1px solid var(--border)}
.nav-drawer ul{list-style:none;margin:0;padding:0}
.nav-drawer a{display:flex;align-items:center;gap:12px;width:100%;min-height:48px;padding:12px;border-radius:var(--r-btn);text-decoration:none}
.nav-drawer a svg{width:18px;height:18px}
.nav-drawer a:hover,.nav-drawer a[aria-current]{background:var(--panel-2)}
.drawer-languages{border-top:1px solid var(--border);margin-top:16px;padding-top:16px}
.nav-veil{position:fixed;inset:var(--header-bottom) 0 0;z-index:47;background:var(--veil);border:0;width:100%;padding:0}
html.nav-open{overflow:hidden}
.site-footer{background:var(--panel-2);border-top:1px solid var(--border);padding-top:56px;padding-bottom:24px}
.footer-grid{display:grid;grid-template-columns:1.4fr 1fr 1.2fr;gap:48px}
.footer-brand p{max-width:360px;margin-top:20px;color:var(--muted);line-height:1.8}
.footer-title{font-size:15px;font-weight:700;margin:0 0 16px}
.footer-links{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px 16px;list-style:none;margin:0;padding:0}
.footer-links a{display:inline-flex;align-items:center;min-height:28px;font-size:14px;color:var(--muted);text-decoration:none}
.footer-links a:hover{text-decoration:underline;color:var(--text)}
.footer-languages{display:flex;flex-wrap:wrap;gap:8px 20px;margin-top:32px;padding-top:24px;border-top:1px solid var(--border)}
.footer-languages a{display:inline-flex;align-items:center;min-height:28px;font-size:14px}
.footer-bottom{display:flex;align-items:center;justify-content:space-between;flex-wrap:wrap;gap:12px;margin-top:20px;color:var(--muted);font-size:13px}
.footer-legal{display:flex;gap:20px}
.footer-legal a{display:inline-flex;align-items:center;min-height:28px}
.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-width:0;max-width:100%;overflow:hidden;margin-top:24px;margin-bottom:24px}
#server-status+*{margin-top:24px}
.prose{line-height:1.9;overflow-wrap:break-word}
.prose h2{margin-top:1.8em;margin-bottom:.6em}
.prose h3{margin-top:1.5em}
.prose li+li{margin-top:.5em}
.prose a{color:var(--accent-dark)}
.prose a.btn--primary,.prose a.btn-primary{color:var(--white)}
.prose img{border-radius:var(--r-panel)}
.decorated,.stripe-halo{position:relative;overflow-x:clip;max-width:100%}
@media(min-width:1025px){.nav-drawer,.nav-veil{display:none}}
@media(max-width:1280px){.mainnav a{padding-inline:8px}.topbar__row{gap:16px}.mark__zh{display:none}}
@media(max-width:1180px){.mainnav a{padding-inline:7px;gap:4px}.mainnav ul{gap:3px}.lang{padding-inline:8px}}
@media(max-width:1100px){.mainnav{display:none}.menu-toggle{display:inline-flex}.topbar__tools{margin-left:auto}.topbar__row{justify-content:space-between}.mark__zh{display:inline}}
@media(max-width:768px){
  :root{--section-space:48px}
  h1{font-size:36px;line-height:1.15}
  h2{font-size:30px}
  .card-grid{grid-template-columns:minmax(0,1fr)}
  .footer-grid{grid-template-columns:minmax(0,1fr);gap:28px}
  .cta-row{flex-wrap:wrap}
  .notice__row{padding-block:7px;flex-wrap:wrap;gap:4px 10px;font-size:12px}
  .mark__zh{display:none}
}
@media(max-width:640px){
  :root{--gutter:16px}
  .no-break{white-space:normal}
  #site-header .notice{display:none}
  .topbar__row{display:flex;align-items:center;flex-wrap:nowrap;gap:8px}
  .topbar__row>.mark{min-width:0;flex-shrink:1;min-height:44px}
  .nav-drawer{padding:8px var(--gutter)}
  .nav-drawer ul{display:block;width:100%}
  .nav-drawer a{min-height:44px;padding:8px 12px}
  .drawer-languages{margin-top:4px;padding-top:4px}
  .drawer-languages a{font-size:14px}
  .topbar__row>.topbar__tools{flex:0 0 auto;align-items:center;flex-wrap:nowrap}
  .topbar__tools{flex-shrink:0}
  .topbar__tools .login{display:none}
  .topbar__tools{gap:4px;margin-left:auto}
  .mark{gap:7px}
  .mark__en{font-size:16px}
  .mark img{width:44px;height:44px}
  .login{padding:0 12px}
  .login svg{display:none}
  .lang span{display:none}
  .lang{padding-inline:7px}
  .panel,.card{padding:20px}
  .tilt,.decorative-tilt,.chip--refund{transform:none}
  .decorated,.stripe-halo{max-width:100%}
  .footer-bottom{align-items:flex-start;flex-direction:column}
}
@media(prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal,.reveal.pending,.reveal.shown{opacity:1;transform:none;transition:none}
  *,*::before,*::after{animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important}
}