:root {
  --bg:#FFFFFF;
  --bg-panel:#FBF8EF;
  --bg-panel-2:#F5F7FA;
  --border:#E3E7EE;
  --accent:#1B6EF3;
  --accent-dark:#0F4FC4;
  --accent-hi:#4A8DF8;
  --accent-soft:#EAF2FE;
  --accent-line:rgba(27,110,243,.2);
  --accent-ring:rgba(27,110,243,.16);
  --text:#0B1530;
  --text-muted:#5A6478;
  --text-sky:#22355A;
  --success:#1FA463;
  --warn:#E8A317;
  --error:#E5484D;
  --white:#FFFFFF;
  --switch-off:#CBD2DC;
  --on-accent-soft:rgba(255,255,255,.22);
  --sky-top:#6FB8F2;
  --sky-mid:#A6D5F8;
  --sky-bottom:#CDE8FC;
  --cloud:#FFFFFF;
  --cloud-shade:#DCEEFC;
  --hill-far:#9ECFCF;
  --hill-mid:#A9DA7C;
  --hill-near:#5BB548;
  --hill-near-hi:#7DC95F;
  --tree:#2F8E45;
  --tree-hi:#4DAA55;
  --trunk:#6F5A42;
  --glass:rgba(255,255,255,.55);
  --glass-strong:rgba(255,255,255,.8);
  --glass-line:rgba(255,255,255,.92);
  --glass-frame:rgba(255,255,255,.42);
  --veil:rgba(11,21,48,.3);
  --clear:transparent;
  --shadow-soft:0 1px 2px rgba(11,21,48,.06),0 8px 20px -10px rgba(11,21,48,.2);
  --shadow-pill:0 6px 14px -6px rgba(15,79,196,.55);
  --shadow-card:0 2px 4px rgba(11,21,48,.05),0 18px 36px -12px rgba(11,21,48,.24),0 40px 70px -30px rgba(15,79,196,.32);
  --shadow-window:0 2px 6px rgba(11,21,48,.06),0 28px 56px -20px rgba(11,21,48,.3),0 80px 140px -40px rgba(15,79,196,.4);
  --shadow-cta:0 12px 24px -8px rgba(15,79,196,.55),inset 0 1px 0 rgba(255,255,255,.3);
  --shadow-knob:0 1px 3px rgba(11,21,48,.25);
  --radius-hero:40px;
  --radius-mobile:28px;
  --radius-frame:32px;
  --radius-window:22px;
  --radius-card:20px;
  --radius-form:18px;
  --radius-code:12px;
  --radius-ctl:10px;
  --radius-mark:9px;
  --radius-key:8px;
  --radius-check:5px;
  --radius-pill:999px;
  --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","Hiragino Sans GB","Microsoft YaHei",system-ui,-apple-system,"Segoe UI",sans-serif;
  --font-mono:"JetBrains Mono",ui-monospace,"SFMono-Regular",Menlo,Consolas,"Liberation Mono",monospace;
  --gutter:24px;
  --reading-width:1120px;
  --header-width:1280px;
  --header-height:68px;
  --space-section:80px;
  --duration:220ms;
}
*,*::before,*::after { box-sizing:border-box; }
html { margin:0; padding:0; scroll-behavior:smooth; scroll-padding-top:24px; }
body { margin:0; padding:0; background:var(--bg); color:var(--text); font:16px/1.6 var(--font-body); -webkit-font-smoothing:antialiased; text-rendering:optimizeLegibility; }
html.nav-open { overflow:hidden; }
[hidden] { display:none !important; }
img,svg { max-width:100%; }
img { height:auto; }
button,input,select,textarea { font:inherit; }
button,a,input,summary { -webkit-tap-highlight-color:var(--accent-ring); }
button { cursor:pointer; }
a { color:var(--accent-dark); text-underline-offset:4px; }
a:hover { color:var(--accent); }
:focus-visible { outline:3px solid var(--accent); outline-offset:4px; }
button:disabled { cursor:not-allowed; }
h1,h2,h3,h4 { font-family:var(--font-display); color:var(--text); text-wrap:balance; overflow-wrap:break-word; }
h1 { margin:22px 0 0; font-size:clamp(34px,3.4vw,48px); font-weight:800; line-height:1.14; letter-spacing:-.02em; }
h2 { margin:0 0 24px; font-size:clamp(26px,3vw,38px); font-weight:800; line-height:1.25; letter-spacing:-.02em; }
h3 { margin:0 0 14px; font-size:23px; line-height:1.35; font-weight:800; }
p { margin:0 0 18px; }
ul,ol { padding-left:1.5em; }
li + li { margin-top:6px; }
code,kbd,pre { font-family:var(--font-mono); }
code { overflow-wrap:anywhere; font-size:.9em; }
pre { max-width:100%; min-width:0; overflow-x:auto; padding:20px; border:1px solid var(--border); border-radius:var(--radius-code); background:var(--bg-panel-2); color:var(--text); font-size:13px; line-height:1.8; tab-size:2; }
pre code { overflow-wrap:normal; word-break:normal; white-space:pre; font-size:inherit; }
hr { border:0; border-top:1px solid var(--border); margin:32px 0; }
:where(main,section,article,aside,nav,div,li) { min-width:0; }
:where(.grid,.card-grid,.footer-grid,.tab-detail) > * { min-width:0; }
svg.icon,.icon, .dot { flex-shrink:0; }
.icon { width:20px; height:20px; }
.wrap { width:100%; max-width:calc(var(--reading-width) + var(--gutter) * 2); margin-inline:auto; padding-inline:var(--gutter); }
.section { padding-top:var(--space-section); padding-bottom:var(--space-section); }
.section-heading { max-width:760px; margin:0 auto 36px; text-align:center; }
.section-heading p,.muted { color:var(--text-muted); }
.keyword { white-space:nowrap; }
.accent { color:var(--accent-dark); }
.center { text-align:center; }
.prose { max-width:800px; margin-inline:auto; line-height:1.9; }
.prose h2 { margin-top:56px; scroll-margin-top:28px; }
.prose h3 { margin-top:32px; scroll-margin-top:28px; }
.prose :where(p,li) { overflow-wrap:break-word; }
.prose :where(div,section) { min-width:0; max-width:100%; }
.button,.ghost,.cta { display:inline-flex; align-items:center; justify-content:center; gap:10px; min-height:48px; padding:12px 24px; border:1px solid var(--clear); border-radius:var(--radius-pill); background:var(--accent); color:var(--white); font-size:15px; font-weight:700; line-height:1.4; text-decoration:none; text-align:center; }
.button:hover,.button.is-hover { background:var(--accent-dark); color:var(--white); }
.button:active { box-shadow:inset 0 0 0 2px var(--accent-dark); }
.button--secondary,.ghost { background:var(--white); color:var(--text); border-color:var(--border); box-shadow:var(--shadow-soft); }
.button--secondary:hover,.ghost:hover { background:var(--bg-panel-2); color:var(--accent-dark); }
.button--soft { background:var(--accent-soft); color:var(--accent-dark); border-color:var(--accent-line); }
.button--soft:hover { background:var(--accent-soft); color:var(--text); }
.button:disabled,.button[aria-disabled="true"] { background:var(--bg-panel-2); color:var(--text-muted); border-color:var(--border); box-shadow:none; }
.button.is-focus { outline:3px solid var(--accent-ring); outline-offset:4px; }
.actions { display:flex; flex-wrap:wrap; align-items:center; gap:14px; margin-top:26px; }
.card { padding:28px; border:1px solid var(--border); border-radius:var(--radius-card); background:var(--white); color:var(--text); box-shadow:var(--shadow-soft); }
.card-grid { display:grid; grid-template-columns:repeat(3,minmax(0,1fr)); gap:24px; }
.panel { position:relative; overflow-x:clip; margin-inline:24px; padding-top:64px; padding-bottom:64px; border-radius:var(--radius-hero); background:var(--bg-panel); color:var(--text); }
.panel--cool { background:var(--bg-panel-2); color:var(--text); }
.decorated { position:relative; overflow-x:clip; }
.sr-only { position:absolute; width:1px; height:1px; padding:0; margin:-1px; overflow:hidden; clip-path:inset(50%); white-space:nowrap; border:0; }

/* 独立于正文阅读宽度的顶栏。 */
#site-header,.preview-header { position:relative; z-index:100; background:var(--bg); color:var(--text); }
.topbar { position:relative; height:var(--header-height); width:100%; max-width:min(100%,calc(var(--header-width) + var(--gutter) * 2)); margin-inline:auto; padding-inline:var(--gutter); display:flex; align-items:center; gap:48px; }
.brand { display:inline-flex; align-items:center; gap:10px; flex-shrink:0; text-decoration:none; color:var(--text); font:800 18px/1.2 var(--font-display); letter-spacing:-.01em; white-space:nowrap; }
.brand img { display:block; width:32px; height:32px; flex-shrink:0; }
.mainnav { flex:1; min-width:0; }
.mainnav ul { display:flex; align-items:center; list-style:none; margin:0; padding:0; gap:clamp(18px,2.35vw,34px); }
.mainnav li { margin:0; flex-shrink:0; }
.mainnav a { display:block; padding-top:14px; padding-bottom:14px; color:var(--text-muted); font-size:15px; font-weight:500; text-decoration:none; white-space:nowrap; }
.mainnav a:hover { color:var(--text); }
.mainnav a[aria-current="page"] { color:var(--text); font-weight:700; }
.header-tools { margin-left:auto; display:flex; align-items:center; gap:8px; flex-shrink:0; }
.language-picker { position:relative; }
.lang { appearance:none; border:0; min-height:38px; padding:10px 16px; border-radius:var(--radius-pill); background:var(--bg-panel-2); color:var(--text); font:600 14px/1.2 var(--font-body); white-space:nowrap; }
.lang span[aria-hidden] { color:var(--text-muted); margin-left:4px; }
.language-menu { position:absolute; right:0; top:calc(100% + 10px); width:190px; margin:0; padding:8px; list-style:none; background:var(--white); color:var(--text); border:1px solid var(--border); border-radius:var(--radius-card); box-shadow:var(--shadow-card); }
.language-menu li { margin:0; }
.language-menu a { display:flex; align-items:center; min-height:44px; padding:10px 14px; border-radius:var(--radius-ctl); color:var(--text); text-decoration:none; }
.language-menu a:hover,.language-menu a[aria-current] { background:var(--bg-panel-2); color: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(--radius-pill); background:var(--white); color:var(--text); }
.menu-toggle svg { width:22px; height:22px; }
.mobile-nav { position:absolute; z-index:3; top:var(--header-height); left:0; right:0; padding:16px var(--gutter) 24px; max-height:calc(100dvh - var(--header-height)); overflow-y:auto; overscroll-behavior:contain; background:var(--white); color:var(--text); border-bottom:1px solid var(--border); box-shadow:var(--shadow-soft); }
.mobile-nav ul { list-style:none; padding:0; margin:0; }
.mobile-nav li { margin:0; }
.mobile-nav a { display:flex; align-items:center; width:100%; min-height:46px; padding:12px 16px; color:var(--text); text-decoration:none; border-radius:var(--radius-ctl); }
.mobile-nav a:hover,.mobile-nav a[aria-current] { background:var(--bg-panel-2); color:var(--accent-dark); }
.mobile-languages { margin-top:16px; padding-top:16px; border-top:1px solid var(--border); }
.mobile-languages p { padding-inline:16px; margin-bottom:6px; color:var(--text-muted); font-size:13px; }
.nav-veil { position:fixed; z-index:90; inset:var(--header-height) 0 0; border:0; padding:0; background:var(--veil); color:var(--text); }
.site-footer { margin-top:48px; padding-top:56px; padding-bottom:28px; border-top:1px solid var(--border); background:var(--bg); color:var(--text); }
.footer-grid { display:grid; grid-template-columns:1.3fr 1fr 1.2fr .8fr; gap:40px; }
.footer-brand p { max-width:280px; margin-top:20px; font-size:14px; color:var(--text-muted); }
.footer-title { margin:0 0 16px; font-size:14px; font-weight:800; }
.footer-links { list-style:none; padding:0; margin:0; }
.footer-links li { margin:0; }
.footer-links a { display:inline-block; padding-top:5px; padding-bottom:5px; color:var(--text-muted); text-decoration:none; font-size:14px; overflow-wrap:anywhere; }
.footer-links a:hover { color:var(--accent-dark); }
.footer-bottom { display:flex; flex-wrap:wrap; gap:16px; justify-content:space-between; align-items:center; margin-top:40px; padding-top:22px; border-top:1px solid var(--border); color:var(--text-muted); font-size:13px; }
.footer-bottom p { margin:0; }
.footer-bottom a { color:var(--text-muted); }

/* 无脚本默认可读；脚本只给待观察元素加 pending。 */
.reveal { opacity:1; transform:none; }
.reveal.reveal-pending { opacity:0; transform:translateY(16px); transition:opacity 600ms ease,transform 600ms ease; }
.reveal.shown { opacity:1; transform:none; }
@media (max-width:1279px) {
  .mainnav { display:none; }
  .menu-toggle { display:inline-flex; }
  .header-tools { margin-left:auto; }
  .topbar { gap:24px; }
}
@media (min-width:1280px) {
  .mobile-nav,.nav-veil { display:none; }
}
@media (max-width:768px) {
  h1 { font-size:clamp(24px,5vw,30px); }
  .card-grid { grid-template-columns:repeat(2,minmax(0,1fr)); }
  .footer-grid { grid-template-columns:repeat(2,minmax(0,1fr)); }
}
@media (max-width:640px) {
  :root { --gutter:16px; --header-height:60px; --space-section:52px; }
  .topbar { gap:12px; padding-inline:20px; }
  .brand { font-size:16px; gap:8px; }
  .brand img { width:30px; height:30px; }
  .lang { padding-inline:12px; font-size:12px; }
  .header-tools { gap:5px; margin-left:auto; }
  .panel { margin-inline:10px; border-radius:var(--radius-mobile); padding-top:40px; padding-bottom:40px; }
  .card-grid { grid-template-columns:minmax(0,1fr); }
  .card { padding:22px; }
  .tilt,.float,.float-rule,.float-clip,[data-tilt] { transform:none !important; }
  .footer-grid { gap:28px 20px; }
  .footer-brand { grid-column:1 / -1; }
  .section-heading { margin-bottom:28px; }
}
@media (prefers-reduced-motion:reduce) {
  html { scroll-behavior:auto; }
  .reveal.reveal-pending { opacity:1; transform:none; transition:none; }
}