:root {
  --bg:#FFFFFF;
  --bg-panel:#F5F5F6;
  --bg-panel-2:#ECECEE;
  --border:#E2E2E6;
  --accent:#3B4BD9;
  --accent-dark:#2A35A8;
  --accent-violet:#6B3FD6;
  --text:#141418;
  --text-muted:#5E606A;
  --text-faint:#8D8F99;
  --ink-hover:#2B2C33;
  --success:#1F8A5B;
  --success-ring:rgba(31,138,91,.16);
  --warn:#B7791F;
  --error:#C0392B;
  --sky-top:#EEF1F8;
  --sky-mid:#F4F6FB;
  --bldg-front-hi:#C9CFDD;
  --bldg-front-lo:#A7AFC4;
  --bldg-side-hi:#A9B1C6;
  --bldg-side-lo:#8A93AB;
  --bldg-far-hi:#E3E7EF;
  --bldg-far-lo:#D3D8E4;
  --bldg-near-hi:#BCC3D4;
  --bldg-near-lo:#9AA3BA;
  --bldg-sphere-hi:#E6E9F2;
  --win-line:rgba(255,255,255,.3);
  --glint:rgba(255,255,255,.6);
  --arc:#8E98C8;
  --arc-halo:rgba(142,152,200,.3);
  --dot-gray:#CFD0D6;
  --grid-ink:rgba(20,20,24,.04);
  --ground-shade:rgba(138,147,171,.34);
  --haze:rgba(255,255,255,.62);
  --veil:rgba(255,255,255,.92);
  --edge-hi:rgba(255,255,255,.95);
  --mask-solid:#000000;
  --mask-clear:transparent;
  --flag-red:#C8313D;
  --flag-blue:#253A7A;
  --flag-gold:#E8B23A;
  --flag-black:#1B1B1F;
  --flag-white:#FFFFFF;
  --flag-edge:rgba(20,20,24,.16);
  --shadow-tint:rgba(59,75,217,.10);
  --shadow-float-tint:rgba(59,75,217,.18);
  --shadow-canvas:0 28px 64px var(--shadow-tint);
  --shadow-panel:0 16px 48px var(--shadow-tint);
  --shadow-chip:0 8px 24px var(--shadow-tint);
  --shadow-float:0 14px 40px var(--shadow-float-tint);
  --font-display:"Inter","Noto Sans SC",-apple-system,"PingFang SC","Hiragino Sans","Microsoft YaHei","Malgun Gothic",sans-serif;
  --font-body:"Inter","Noto Sans SC",-apple-system,"PingFang SC","Hiragino Sans","Microsoft YaHei","Malgun Gothic",sans-serif;
  --font-mono:"JetBrains Mono",ui-monospace,"SFMono-Regular",Menlo,Consolas,monospace;
  --weight-regular:400;
  --weight-medium:500;
  --weight-brand:600;
  --text-xs:12px;
  --text-sm:14px;
  --text-nav:15px;
  --text-button:16px;
  --text-body:17px;
  --text-lead:18px;
  --text-brand:19px;
  --text-h3:24px;
  --text-h2:36px;
  --h1-size:64px;
  --leading-body:1.6;
  --leading-title:1.1;
  --tracking-display:-.03em;
  --tracking-cjk:-.02em;
  --radius-0:0;
  --radius-canvas:4px;
  --radius-pill:999px;
  --radius-dot:50%;
  --notice-h:40px;
  --nav-h:64px;
  --header-edge:104px;
  --gutter:24px;
  --inset:24px;
  --copy-x:56px;
  --copy-w:520px;
  --content-width:1280px;
  --reading-width:820px;
  --section-gap:88px;
  --toc-top:16px;
  --anchor-offset:88px;
  --ease-out:cubic-bezier(.22,.61,.36,1);
  --transition-fast:.18s;
  --transition-reveal:.35s;
}
*,*::before,*::after {box-sizing:border-box}
html {-webkit-text-size-adjust:100%;scroll-padding-top:var(--anchor-offset);scroll-behavior:smooth}
body {margin:0;background:var(--bg);color:var(--text);font-family:var(--font-body);font-size:var(--text-body);line-height:var(--leading-body);-webkit-font-smoothing:antialiased}
img {display:block;max-width:100%;height:auto}
svg {flex-shrink:0}
a {color:var(--accent);text-underline-offset:3px}
button,input,select,textarea {font:inherit}
button {color:inherit;cursor:pointer}
button,a,summary {-webkit-tap-highlight-color:var(--mask-clear)}
button {border:0}
button:disabled {cursor:not-allowed}
:focus-visible {outline:2px solid var(--accent);outline-offset:3px}
[hidden] {display:none!important}
h1,h2,h3,h4 {font-family:var(--font-display);font-weight:var(--weight-regular);text-wrap:balance}
h1 {font-size:clamp(52px,4.45vw,72px);line-height:var(--leading-title);letter-spacing:var(--tracking-cjk);margin:0 0 24px}
h2 {font-size:var(--text-h2);line-height:1.25;letter-spacing:var(--tracking-cjk);margin:0 0 24px}
h3 {font-size:var(--text-h3);line-height:1.35;margin:0 0 16px}
p {margin:0 0 20px}
ul,ol {padding-left:1.4em}
li+li {margin-top:6px}
strong {font-weight:var(--weight-brand)}
pre,code {font-family:var(--font-mono);font-size:.88em}
code {overflow-wrap:anywhere}
pre {max-width:100%;overflow-x:auto;padding:20px;background:var(--bg-panel);border:1px solid var(--border)}
pre code {overflow-wrap:normal;white-space:pre}
hr {border:0;border-top:1px solid var(--border);margin:32px 0}
.no-break {white-space:nowrap}
.wrap {width:100%;max-width:var(--content-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-gap);padding-bottom:var(--section-gap)}
.grid {display:grid;gap:24px}
.grid-3 {grid-template-columns:repeat(3,minmax(0,1fr))}
.grid-5 {grid-template-columns:repeat(5,minmax(0,1fr))}
.grid>* {min-width:0}
.flex-row {display:flex;align-items:center;gap:12px;flex-wrap:wrap}
.muted {color:var(--text-muted)}
.mono {font-family:var(--font-mono);font-variant-numeric:tabular-nums}
.kicker {font-family:var(--font-mono);font-size:var(--text-xs);color:var(--text-muted);margin-bottom:16px}
.panel,.card {min-width:0;background:var(--bg-panel);padding:32px;border-radius:var(--radius-0)}
.panel {box-shadow:var(--shadow-panel),inset 0 1px 0 var(--edge-hi)}
.card {border:1px solid var(--border)}
.btn {display:inline-flex;align-items:center;justify-content:center;gap:10px;min-height:48px;padding:10px 24px;border-radius:var(--radius-0);font-size:var(--text-button);font-weight:var(--weight-medium);text-decoration:none;transition:background-color var(--transition-fast) ease;flex-shrink:0;white-space:nowrap}
.btn svg {width:14px;height:14px}
.btn-primary {background:var(--text);color:var(--bg)}
.btn-primary:hover,.btn-primary.is-hover {background:var(--ink-hover)}
.btn-secondary {background:var(--bg-panel-2);color:var(--text)}
.btn-secondary:hover,.btn-secondary.is-hover {background:var(--border)}
.btn:disabled,.btn[aria-disabled="true"] {opacity:.5;pointer-events:none}
.btn.is-focus {outline:2px solid var(--accent);outline-offset:3px}
.cta-row {display:flex;flex-wrap:wrap;gap:12px;margin:0 0 24px}
.notice {min-height:var(--notice-h);display:flex;align-items:center;justify-content:center;gap:16px;padding:0 var(--inset);background:linear-gradient(90deg,var(--accent),var(--accent-violet) 55%,var(--accent));color:var(--bg);font-size:var(--text-sm)}
.notice p {margin:0;display:flex;align-items:center;gap:14px;flex-wrap:wrap}
.notice p a {color:inherit;text-decoration:underline}
.notice-pill {display:inline-flex;align-items:center;justify-content:center;gap:6px;min-height:26px;padding:0 12px;border-radius:var(--radius-pill);background:var(--bg);color:var(--text);font-size:var(--text-xs);font-weight:var(--weight-medium);text-decoration:none;white-space:nowrap}
.masthead {height:var(--nav-h);display:grid;grid-template-columns:1fr auto 1fr;align-items:center;padding:0 var(--inset);background:var(--bg);position:relative;z-index:42}
.brand {display:inline-flex;align-items:center;gap:10px;text-decoration:none;justify-self:start;color:var(--text);white-space:nowrap}
.brand img {width:28px;height:28px;flex-shrink:0}
.brand-en {font-size:var(--text-brand);font-weight:var(--weight-brand);letter-spacing:var(--tracking-cjk)}
.desktop-nav {flex:1;min-width:0}
.nav-list {display:flex;align-items:center;list-style:none;margin:0;padding:0;gap:6px}
.nav-list>li {position:relative;margin:0}
.nav-list>li>a,.more-btn {display:inline-flex;align-items:center;gap:6px;min-height:40px;padding:0 14px;font-size:var(--text-nav);background:var(--mask-clear);color:var(--text);text-decoration:none;white-space:nowrap}
.nav-list a[aria-current="page"],.more-btn[aria-current="page"] {box-shadow:inset 0 -2px 0 var(--text)}
.nav-list a:hover,.more-btn:hover {color:var(--text-muted)}
.more-btn svg,.lang svg {width:12px;height:12px}
.more-panel {position:absolute;z-index:45;top:calc(100% + 6px);left:0;min-width:168px;padding:8px 0;background:var(--bg);border:1px solid var(--border);box-shadow:var(--shadow-panel),inset 0 1px 0 var(--edge-hi)}
.more-panel a {display:flex;align-items:center;min-height:40px;padding:8px 16px;font-size:var(--text-sm);text-decoration:none;color:var(--text)}
.more-panel a:hover {background:var(--bg-panel)}
.nav-tools {justify-self:end;display:flex;align-items:center;gap:8px;flex-shrink:0;flex-wrap:nowrap}
.language {position:relative}
.lang {display:inline-flex;align-items:center;justify-content:center;gap:6px;width:auto;min-width:44px;min-height:36px;padding:0 12px;background:var(--bg-panel);font-size:var(--text-sm);color:var(--text);white-space:nowrap}
.lang span {white-space:nowrap}
.language-panel {position:absolute;z-index:48;right:0;top:calc(100% + 8px);min-width:164px;padding:8px;background:var(--bg);border:1px solid var(--border);box-shadow:var(--shadow-panel)}
.language-panel a {display:flex;align-items:center;min-height:40px;padding:8px 12px;text-decoration:none;color:var(--text);font-size:var(--text-sm)}
.language-panel a:hover,.language-panel a[aria-current="true"] {background:var(--bg-panel)}
.btn-login {display:inline-flex;align-items:center;justify-content:center;min-height:36px;padding:0 18px;background:var(--text);color:var(--bg);font-size:var(--text-sm);font-weight:var(--weight-medium);text-decoration:none;white-space:nowrap}
.btn-login:hover {background:var(--ink-hover)}
.menu-toggle {display:none;align-items:center;justify-content:center;flex-direction:column;gap:4px;min-width:44px;min-height:44px;background:var(--bg-panel);color:var(--text)}
.menu-line {display:block;width:20px;height:2px;background:currentColor}
.nav-drawer {display:none}
.nav-shade {display:none}
html.nav-open {overflow:hidden}
.site-footer {background:var(--bg-panel);border-top:1px solid var(--border);padding-top:56px;padding-bottom:32px}
.footer-grid {display:grid;grid-template-columns:1.5fr 1fr 1fr 1fr;gap:40px}
.footer-grid>* {min-width:0}
.footer-brand p {margin-top:20px;color:var(--text-muted);font-size:var(--text-sm);max-width:30em}
.footer-title {font-size:var(--text-nav);font-weight:var(--weight-medium);margin:0 0 16px}
.footer-list {list-style:none;margin:0;padding:0}
.footer-list li {margin:0}
.footer-list a {display:inline-flex;align-items:center;min-height:32px;color:var(--text-muted);font-size:var(--text-sm);text-decoration:none;overflow-wrap:anywhere}
.footer-list a:hover {color:var(--accent)}
.footer-bottom {border-top:1px solid var(--border);margin-top:40px;padding-top:24px;display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:16px;font-size:var(--text-sm);color:var(--text-muted)}
.footer-legal {display:flex;flex-wrap:wrap;gap:8px 20px}
.footer-legal a {color:inherit;display:inline-flex;align-items:center;min-height:28px}
.reveal {transition:opacity var(--transition-reveal) var(--ease-out),transform var(--transition-reveal) var(--ease-out)}
.reveal.pending {opacity:0;transform:translateY(16px)}
.reveal.shown {opacity:1;transform:none}
#server-status {position:relative;display:block;min-height:120px;overflow:hidden;max-width:100%;margin-block:24px}
#server-status+* {margin-top:32px}
#server-status>* {min-width:0;max-width:100%}
.decor-region {position:relative;overflow-x:clip}
.prose {overflow-wrap:break-word}
.prose>p,.prose>ul,.prose>ol {line-height:1.85}
.prose h2 {margin-top:56px}
.prose h3 {margin-top:32px}
@media(max-width:1360px) {
  :root {--copy-x:48px;--copy-w:460px;--h1-size:56px}
}
@media(max-width:1100px) {
  .masthead {display:flex;gap:16px}
  .desktop-nav {display:none}
  .nav-tools {margin-left:auto}
  .menu-toggle {display:flex}
  .nav-drawer {position:fixed;z-index:40;inset:var(--header-edge) 0 auto;max-height:calc(100dvh - var(--header-edge));height:calc(100dvh - var(--header-edge));overflow-y:auto;overscroll-behavior:contain;background:var(--bg);padding:16px var(--gutter) 32px}
  .nav-drawer:not([hidden]) {display:block}
  .nav-drawer a {display:flex;align-items:center;width:100%;min-height:44px;padding:12px 16px;text-decoration:none;color:var(--text);border-bottom:1px solid var(--border)}
  .nav-drawer a[aria-current="page"] {background:var(--bg-panel)}
  .drawer-languages {margin-top:24px;border-top:1px solid var(--border)}
  .nav-shade {position:fixed;z-index:39;inset:var(--header-edge) 0 0;background:var(--veil);width:100%}
  .nav-shade:not([hidden]) {display:block}
  .footer-grid {grid-template-columns:repeat(2,minmax(0,1fr))}
  .grid-5 {grid-template-columns:repeat(3,minmax(0,1fr))}
}
@media(max-width:768px) {
  :root {--gutter:20px;--inset:12px;--h1-size:36px;--text-h2:28px;--text-h3:22px;--section-gap:56px}
  h1 {font-size:var(--h1-size)}
  .notice {padding:8px 12px;gap:8px 12px;flex-wrap:wrap;font-size:var(--text-xs)}
  .notice p {justify-content:center;gap:4px 10px}
  .grid-3,.grid-5 {grid-template-columns:1fr}
  .panel,.card {padding:24px}
  .btn {min-height:46px;padding-inline:20px}
  .nav-tools {gap:6px;margin-left:auto}
  .lang {padding-inline:8px;font-size:var(--text-xs)}
}
@media(max-width:640px) {
  .no-break {white-space:normal}
  .tilt,[data-tilt] {transform:none}
  .decor-region>* {max-width:100%}
  .footer-grid {grid-template-columns:1fr;gap:28px}
}
@media(max-width:380px) {
  :root {--gutter:16px;--text-brand:16px}
  .brand {gap:6px}
  .brand img {width:24px;height:24px}
  .masthead {gap:6px}
  .btn-login {padding-inline:10px}
  .lang {padding-inline:5px}
  .lang svg {display:none}
}
@media(prefers-reduced-motion:reduce) {
  html {scroll-behavior:auto}
  .reveal,.reveal.pending,.reveal.shown {opacity:1;transform:none;transition:none}
  .btn,.more-panel,.btn-login {transition:none}
}