/* ============================================================
   博业官网 · /assets/site.css
   共享外壳：reset / 变量 / 中文排版 / 页头 / 页脚 / 通用组件
   ============================================================ */

/* ---------- 1. Reset ---------- */
*,*::before,*::after{box-sizing:border-box}
html{-webkit-text-size-adjust:100%;scroll-behavior:smooth}
@media (min-width:901px){html{scroll-padding-top:112px}}
body,h1,h2,h3,h4,h5,p,figure,blockquote,ul,ol,dl,dd{margin:0}
ul,ol{padding:0}
ul[class],ol[class]{list-style:none}
img,svg,video{display:block;max-width:100%}
a{color:inherit;text-decoration:none}
button,input,select,textarea{font:inherit;color:inherit}
button{background:none;border:0;padding:0;cursor:pointer}
kbd{font-family:"SFMono-Regular",ui-monospace,Menlo,Consolas,monospace}
:where(a,button,input,summary,[tabindex]):focus-visible{outline:2px solid #A8442A;outline-offset:3px}
.site-header :focus-visible{outline-color:#8FBFC4}
.site-footer :focus-visible{outline-color:#8FBFC4}

/* ---------- 2. 设计变量 ---------- */
:root{
  --mist:#F4F1EA;
  --paper:#E7E1D3;
  --ochre:#A8442A;
  --ochre-deep:#74301F;
  --lake:#1F6E7A;
  --lake-soft:#8FBFC4;
  --deep:#123F47;
  --tea:#2F4B3A;
  --wine:#6B2B3A;
  --indigo:#3B2F5C;
  --ink:#1D1D1B;
  --glass:rgba(255,255,255,.58);
  --line:rgba(29,29,27,.14);
  --line-strong:rgba(29,29,27,.3);
  --line-light:rgba(244,241,234,.2);

  --shell:1240px;
  --header-size:96px;
  --r:2px;

  --font-display:"PingFang SC","Source Han Sans SC","Noto Sans SC","Hiragino Sans GB","Microsoft YaHei",system-ui,-apple-system,sans-serif;
  --font-body:"PingFang SC","Source Han Sans SC","Noto Sans SC","Hiragino Sans GB","Microsoft YaHei",system-ui,-apple-system,sans-serif;
  --font-mono:"SFMono-Regular",ui-monospace,Menlo,Consolas,"Noto Sans Mono CJK SC","Courier New",monospace;

  --ease:cubic-bezier(.22,.61,.36,1);
}

/* ---------- 3. 基础与中文排版 ---------- */
body{
  display:flex;
  flex-direction:column;
  min-height:100vh;
  background-color:var(--mist);
  background-image:repeating-linear-gradient(to bottom,rgba(29,29,27,.035) 0 1px,transparent 1px 34px);
  color:var(--ink);
  font-family:var(--font-body);
  font-size:16.5px;
  line-height:1.75;
  font-weight:400;
  letter-spacing:.01em;
  -webkit-font-smoothing:antialiased;
  text-rendering:optimizeLegibility;
}
#main-content{display:block;flex:1 0 auto}

h1,h2,h3,h4{font-family:var(--font-display);font-weight:800;line-height:1.14;letter-spacing:-.015em;text-wrap:balance}
h1{font-size:clamp(2.4rem,5.6vw,5rem);line-height:1.04;letter-spacing:-.03em}
h2{font-size:clamp(1.5rem,2.6vw,2rem);line-height:1.2}
h3{font-size:1.25rem;font-weight:700;line-height:1.35}
h4{font-size:1.05rem;font-weight:700}
p{max-width:68ch}
small{font-size:.82rem}
strong{font-weight:700;color:var(--ink)}
a:not([class]){color:var(--lake);border-bottom:1px solid rgba(31,110,122,.4)}
a:not([class]):hover{color:var(--deep);border-bottom-color:var(--deep)}
::selection{background:rgba(168,68,42,.22);color:var(--ochre-deep)}

/* ---------- 4. 工具类 ---------- */
.visually-hidden{position:absolute!important;width:1px;height:1px;margin:-1px;padding:0;overflow:hidden;clip:rect(0 0 0 0);clip-path:inset(50%);white-space:nowrap;border:0}
.skip-link{position:absolute;left:14px;top:-64px;z-index:200;background:var(--ochre);color:#fff;font-size:.9rem;font-weight:600;padding:.7em 1.1em;border-radius:0 0 var(--r) var(--r);transition:top .18s var(--ease)}
.skip-link:focus,.skip-link:focus-visible{top:0;color:#fff}
.container{width:100%;max-width:var(--shell);margin-inline:auto;padding-inline:clamp(16px,4vw,40px)}
.mono{font-family:var(--font-mono);font-variant-numeric:tabular-nums;letter-spacing:.02em}
.section{padding-block:clamp(40px,6vw,88px)}
.section--tight{padding-block:clamp(24px,3.5vw,48px)}
.stack>*+*{margin-top:1.2em}
.section-head{display:grid;gap:.65rem;margin-bottom:clamp(18px,3vw,32px)}
.rule{height:1px;background:var(--line);border:0;margin-block:clamp(20px,3vw,36px)}
.rule--ticks{height:8px;background:repeating-linear-gradient(90deg,var(--line-strong) 0 1px,transparent 1px 12px);border:0}
.eyebrow{display:flex;align-items:center;gap:.65em;font-family:var(--font-mono);font-size:.72rem;letter-spacing:.18em;text-transform:uppercase;color:var(--ochre)}
.eyebrow::before{content:"";width:20px;height:2px;background:var(--ochre);flex:0 0 auto}

/* 网格：12 列错落 */
.grid{display:grid;gap:clamp(16px,2.4vw,32px);grid-template-columns:repeat(12,minmax(0,1fr))}
.span-4{grid-column:span 4}
.span-5{grid-column:span 5}
.span-6{grid-column:span 6}
.span-7{grid-column:span 7}
.span-8{grid-column:span 8}
.span-12{grid-column:span 12}
.tilt{margin-top:clamp(0px,3vw,48px)}
@media (max-width:900px){
  .span-4,.span-5,.span-6,.span-7,.span-8{grid-column:span 12}
  .tilt{margin-top:0}
}

/* ---------- 5. 索引签与按钮 ---------- */
.tag{display:inline-flex;align-items:center;gap:.4em;font-family:var(--font-mono);font-size:.76rem;line-height:1;padding:.45em .6em;border:1px solid var(--line-strong);background:var(--paper);color:var(--ink);border-radius:var(--r);letter-spacing:.02em}
.tag--lake{background:rgba(31,110,122,.12);border-color:rgba(31,110,122,.45);color:#15565f}
.tag--tea{background:rgba(47,75,58,.12);border-color:rgba(47,75,58,.45);color:#2A4536}
.tag--wine{background:rgba(107,43,58,.1);border-color:rgba(107,43,58,.42);color:#5E2734}
.tag--indigo{background:rgba(59,47,92,.1);border-color:rgba(59,47,92,.4);color:#3B2F5C}

.btn{display:inline-flex;align-items:center;justify-content:center;gap:.5em;min-height:44px;padding:.68em 1.15em;border:1px solid transparent;border-radius:var(--r);font-family:var(--font-body);font-size:.94rem;font-weight:600;line-height:1.2;letter-spacing:.01em;transition:background-color .18s var(--ease),color .18s var(--ease),border-color .18s var(--ease),transform .18s var(--ease)}
.btn:active{transform:translateY(1px)}
.btn--ochre{background:var(--ochre);color:#fff}
.btn--ochre:hover{background:var(--ochre-deep);color:#fff}
.btn--deep{background:var(--deep);color:var(--mist)}
.btn--deep:hover{background:#0d3239;color:#fff}
.btn--lake{background:var(--lake);color:#fff}
.btn--lake:hover{background:#175966;color:#fff}
.btn--ghost{border-color:var(--line-strong);color:var(--ink);background:transparent}
.btn--ghost:hover{background:var(--paper);border-color:var(--ochre);color:var(--ochre-deep)}
.btn--glass{background:var(--glass);border-color:rgba(255,255,255,.65);color:var(--ink);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px)}
.btn--glass:hover{background:rgba(255,255,255,.82);border-color:var(--lake)}
.btn--sm{min-height:34px;font-size:.83rem;padding:.4em .8em}

/* ---------- 6. 框景 / 面板 / 图片容器 ---------- */
.frame{position:relative;border:1px solid var(--line-strong);background:rgba(255,255,255,.42);padding:clamp(18px,3vw,34px)}
.frame::before,.frame::after{content:"";position:absolute;width:22px;height:22px;pointer-events:none}
.frame::before{top:-1px;left:-1px;border-top:3px solid var(--ochre);border-left:3px solid var(--ochre)}
.frame::after{bottom:-1px;right:-1px;border-bottom:3px solid var(--ochre);border-right:3px solid var(--ochre)}
.frame__bar{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:.75rem;font-family:var(--font-mono);font-size:.7rem;letter-spacing:.16em;text-transform:uppercase;color:var(--lake);border-bottom:1px solid var(--line);padding-bottom:.65rem;margin-bottom:clamp(14px,2.4vw,26px)}
.frame__folio{color:var(--ochre)}

.panel{background:var(--paper);border:1px solid var(--line-strong);border-radius:var(--r);padding:clamp(16px,2.4vw,28px)}
.panel--glass{background:var(--glass);border-color:rgba(255,255,255,.7);-webkit-backdrop-filter:blur(12px);backdrop-filter:blur(12px);box-shadow:0 22px 46px -32px rgba(18,63,71,.72)}
.panel--deep{background:var(--deep);border-color:var(--deep);color:rgba(244,241,234,.9)}
.panel--deep h2,.panel--deep h3{color:var(--mist)}
.panel--accent-ochre{border-top:3px solid var(--ochre)}
.panel--accent-lake{border-top:3px solid var(--lake)}
.panel--accent-tea{border-top:3px solid var(--tea)}

.media{position:relative;display:block;overflow:hidden;background:var(--paper);border:1px solid var(--line-strong);border-radius:var(--r);margin:0}
.media__img{width:100%;height:100%;object-fit:cover;aspect-ratio:var(--media-ratio,16/10);filter:saturate(.97)}
.media--framed::after{content:"";position:absolute;inset:6px;border:1px solid rgba(244,241,234,.4);pointer-events:none}
.media--placeholder{background-image:repeating-linear-gradient(45deg,rgba(29,29,27,.07) 0 8px,transparent 8px 16px)}
.media__cap{display:block;font-family:var(--font-mono);font-size:.7rem;letter-spacing:.08em;color:rgba(29,29,27,.62);padding-top:.55rem}

.crumbs{display:flex;flex-wrap:wrap;align-items:center;gap:.5rem;padding-block:1rem;font-family:var(--font-mono);font-size:.72rem;letter-spacing:.08em;color:rgba(29,29,27,.6)}
.crumbs__item{display:inline-flex;align-items:center;gap:.5rem}
.crumbs__item[aria-current="page"]{color:var(--ink)}
.crumbs__link{color:var(--lake);border-bottom:1px solid transparent}
.crumbs__link:hover{border-bottom-color:var(--lake)}
.crumbs__sep{opacity:.5}

.tablewrap{overflow-x:auto;-webkit-overflow-scrolling:touch;border:1px solid var(--line-strong);background:rgba(255,255,255,.5)}
.cmp-table{width:100%;min-width:640px;border-collapse:collapse;font-size:.92rem}
.cmp-table th,.cmp-table td{padding:.7rem .85rem;text-align:left;vertical-align:top;border-bottom:1px solid var(--line)}
.cmp-table thead th{background:var(--lake);color:#fff;font-family:var(--font-mono);font-size:.72rem;letter-spacing:.1em;font-weight:600;white-space:nowrap}
.cmp-table tbody tr:nth-child(even){background:rgba(231,225,211,.55)}
.cmp-table tbody th{font-weight:600;color:var(--deep);white-space:nowrap}
.cmp-table .is-active-col{background:rgba(31,110,122,.14)}

.tocrail{display:grid;gap:.25rem;font-size:.82rem}
.tocrail__link{display:block;padding:.35rem .55rem;border-left:2px solid var(--line);color:rgba(29,29,27,.7);transition:color .18s var(--ease),background-color .18s var(--ease),border-color .18s var(--ease)}
.tocrail__link:hover{color:var(--lake);border-left-color:var(--lake-soft)}
.tocrail__link[aria-current="true"]{color:var(--ochre-deep);border-left-color:var(--ochre);background:rgba(168,68,42,.08);font-weight:600}

/* ---------- 7. 站点页头 ---------- */
.site-header{position:sticky;top:0;z-index:90;isolation:isolate;transition:box-shadow .2s var(--ease)}
.site-header[data-scrolled="true"]{box-shadow:0 14px 34px -26px rgba(18,63,71,.95)}

.cmdbar{background:var(--deep);color:var(--mist);border-bottom:1px solid rgba(244,241,234,.12)}
.cmdbar__inner{display:flex;align-items:center;gap:clamp(8px,1.6vw,20px);height:56px;width:100%;max-width:var(--shell);margin-inline:auto;padding-inline:clamp(12px,3vw,28px)}

.brand{display:inline-flex;align-items:center;gap:.6rem;flex:0 0 auto;color:var(--mist)}
.brand__mark{width:30px;height:30px;display:grid;place-items:center;flex:0 0 auto;background:var(--ochre);color:#fff;border-radius:var(--r);font-family:var(--font-display);font-weight:800;font-size:.95rem;line-height:1}
.brand__text{display:grid;gap:1px;line-height:1.05}
.brand__name{font-family:var(--font-display);font-weight:800;font-size:1rem;letter-spacing:.05em;color:inherit}
.brand__sub{font-family:var(--font-mono);font-size:.6rem;letter-spacing:.2em;text-transform:uppercase;color:var(--lake-soft)}

.cmdbar__path{flex:0 0 auto;font-family:var(--font-mono);font-size:.68rem;letter-spacing:.16em;color:rgba(244,241,234,.5);padding-left:.9rem;border-left:1px solid rgba(244,241,234,.18);white-space:nowrap}

.cmd-search{position:relative;flex:1 1 240px;min-width:0;max-width:440px;margin-inline:auto}
.cmd-search__field{display:flex;align-items:center;gap:.55rem;height:34px;padding:0 .65rem;background:var(--glass);border:1px solid rgba(255,255,255,.55);border-radius:var(--r);-webkit-backdrop-filter:blur(10px);backdrop-filter:blur(10px);transition:border-color .18s var(--ease),box-shadow .18s var(--ease)}
.cmd-search__field:focus-within{border-color:var(--lake-soft);box-shadow:0 0 0 3px rgba(143,191,196,.28)}
.cmd-search__icon{width:14px;height:14px;flex:0 0 auto;color:var(--deep)}
.cmd-search__input{flex:1 1 auto;min-width:0;border:0;background:transparent;font-size:.85rem;line-height:1.4;color:var(--ink);padding:0}
.cmd-search__input::placeholder{color:rgba(18,63,71,.62)}
.cmd-search__input:focus{outline:none}
.cmd-search__key{flex:0 0 auto;font-family:var(--font-mono);font-size:.66rem;line-height:1;color:rgba(18,63,71,.6);border:1px solid rgba(18,63,71,.3);border-radius:var(--r);padding:.2em .35em}
.cmd-search__panel{position:absolute;z-index:120;top:calc(100% + 8px);left:0;width:min(430px,calc(100vw - 24px));max-height:min(60vh,360px);overflow:auto;padding:.35rem;background:var(--paper);color:var(--ink);border:1px solid var(--line-strong);border-radius:var(--r);box-shadow:0 22px 44px -22px rgba(18,63,71,.6);list-style:none;margin:0}
.cmd-search__panel[data-open="false"]{display:none}
.cmd-search__item+.cmd-search__item{border-top:1px solid var(--line)}
.cmd-search__hit{display:flex;align-items:baseline;justify-content:space-between;gap:.75rem;padding:.55rem .6rem;border-radius:var(--r)}
.cmd-search__hit:hover,.cmd-search__hit:focus-visible{background:rgba(31,110,122,.12)}
.cmd-search__hit-label{font-size:.9rem;font-weight:500;line-height:1.4}
.cmd-search__hit-meta{flex:0 0 auto;font-family:var(--font-mono);font-size:.66rem;letter-spacing:.12em;color:var(--lake);white-space:nowrap}
.cmd-search__empty{padding:.7rem .6rem;font-size:.84rem;color:rgba(29,29,27,.62)}

.verrail{display:flex;align-items:center;gap:.3rem;flex:0 0 auto}
.verrail__label{font-family:var(--font-mono);font-size:.62rem;letter-spacing:.18em;color:rgba(244,241,234,.48);margin-right:.15rem}
.verrail__btn{font-family:var(--font-mono);font-size:.76rem;line-height:1;padding:.5em .55em;color:rgba(244,241,234,.82);border:1px solid rgba(244,241,234,.24);border-radius:var(--r);transition:background-color .18s var(--ease),color .18s var(--ease),border-color .18s var(--ease)}
.verrail__btn:hover{background:rgba(244,241,234,.14);color:#fff}
.verrail__btn[aria-pressed="true"]{background:var(--lake);border-color:var(--lake);color:#fff}

.cmdbar__cta{flex:0 0 auto}

.navtoggle{display:none;position:relative;flex:0 0 auto;width:40px;height:36px;border:1px solid rgba(244,241,234,.3);border-radius:var(--r);color:var(--mist)}
.navtoggle:hover{background:rgba(244,241,234,.12)}
.navtoggle__bars{display:grid;gap:4px;place-items:center;width:100%;height:100%}
.navtoggle__bar{display:block;width:16px;height:2px;background:currentColor;transition:transform .18s var(--ease),opacity .18s var(--ease)}
.navtoggle[aria-expanded="true"] .navtoggle__bar:nth-child(1){transform:translateY(6px) rotate(45deg)}
.navtoggle[aria-expanded="true"] .navtoggle__bar:nth-child(2){opacity:0}
.navtoggle[aria-expanded="true"] .navtoggle__bar:nth-child(3){transform:translateY(-6px) rotate(-45deg)}

.indexbar{position:relative;background:var(--paper);color:var(--ink);border-bottom:1px solid var(--line-strong)}
.indexbar__inner{display:flex;align-items:center;gap:1rem;width:100%;max-width:var(--shell);min-height:40px;margin-inline:auto;padding-inline:clamp(12px,3vw,28px)}
.indexnav{flex:1 1 auto;min-width:0}
.indexnav__list{display:flex;flex-wrap:wrap;align-items:center;gap:.1rem;margin:0;padding:0;list-style:none}
.indexnav__item{display:block}
.indexnav__link{display:inline-flex;align-items:center;gap:.45em;padding:.5rem .7rem;font-size:.89rem;font-weight:500;color:rgba(29,29,27,.78);border-bottom:2px solid transparent;transition:color .18s var(--ease),background-color .18s var(--ease),border-color .18s var(--ease)}
.indexnav__num{font-family:var(--font-mono);font-size:.64rem;letter-spacing:.06em;color:var(--ochre);opacity:.85}
.indexnav__link:hover{color:var(--ochre-deep);background:rgba(168,68,42,.08)}
.indexnav__link[aria-current="page"]{color:var(--ochre-deep);border-bottom-color:var(--ochre);background:rgba(168,68,42,.1)}
.indexnav__link[aria-current="page"] .indexnav__num{color:var(--ochre-deep);opacity:1}
.quicklink{flex:0 0 auto;display:inline-flex;align-items:center;gap:.35em;font-family:var(--font-mono);font-size:.7rem;letter-spacing:.14em;color:var(--lake);padding:.2em 0;border-bottom:1px solid rgba(31,110,122,.5);transition:color .18s var(--ease),border-color .18s var(--ease)}
.quicklink:hover{color:var(--deep);border-bottom-color:var(--deep)}

.progressbar{position:absolute;left:0;right:0;bottom:0;height:2px;background:rgba(29,29,27,.12);pointer-events:none}
.progressbar__fill{display:block;height:100%;transform:scaleX(0);transform-origin:left center;background:linear-gradient(90deg,var(--ochre),var(--lake-soft))}

/* ---------- 8. 页头响应式 ---------- */
@media (max-width:1100px){
  .cmdbar__path{display:none}
}
@media (max-width:900px){
  .cmdbar__cta{display:none}
  .navtoggle{display:grid;place-items:center}
  .indexbar__inner{min-height:36px}
  .indexnav{display:none}
  .indexnav[data-open="true"]{
    display:block;
    position:absolute;
    left:0;right:0;top:100%;
    z-index:95;
    background:var(--paper);
    border-bottom:1px solid var(--line-strong);
    box-shadow:0 26px 44px -26px rgba(18,63,71,.65);
    padding:.35rem clamp(12px,3vw,28px) 1rem;
    animation:drawerIn .2s var(--ease) both;
  }
  .indexnav__list{flex-direction:column;align-items:stretch;gap:0}
  .indexnav__item+.indexnav__item{border-top:1px solid var(--line)}
  .indexnav__link{display:flex;width:100%;padding:.85rem .2rem;font-size:1rem;border-bottom:0;border-left:2px solid transparent}
  .indexnav__link[aria-current="page"]{border-left-color:var(--ochre);border-bottom:0;background:rgba(168,68,42,.08);padding-left:.7rem}
}
@keyframes drawerIn{from{opacity:0;transform:translateY(-6px)}to{opacity:1;transform:none}}
@media (max-width:720px){
  .verrail{display:none}
  .cmd-search{max-width:none}
}
@media (max-width:420px){
  .brand__sub{display:none}
}

/* ---------- 9. 站点页脚 ---------- */
.site-footer{position:relative;margin-top:auto;background:var(--deep);color:rgba(244,241,234,.82)}
.site-footer::before{content:"";position:absolute;top:0;left:0;right:0;height:8px;background:repeating-linear-gradient(90deg,var(--ochre) 0 2px,transparent 2px 24px);opacity:.6}
.footer__inner{display:grid;gap:clamp(24px,3vw,40px);grid-template-columns:1.4fr 1fr 1fr 1.2fr;width:100%;max-width:var(--shell);margin-inline:auto;padding:clamp(38px,5vw,64px) clamp(16px,4vw,40px) 0}
.footer__brand{display:grid;align-content:start;justify-items:start;gap:0}
.brand--footer{color:var(--mist)}
.footer__note{margin-top:1rem;font-size:.9rem;line-height:1.7;color:rgba(244,241,234,.72);max-width:30ch}
.footer__meta{margin-top:.85rem;font-size:.66rem;letter-spacing:.16em;color:rgba(143,191,196,.9)}
.footer__col{min-width:0}
.footer__title{margin-bottom:.8rem;font-family:var(--font-mono);font-size:.68rem;font-weight:600;letter-spacing:.18em;text-transform:uppercase;color:var(--lake-soft)}
.footer__list{display:grid;gap:.5rem;margin:0;padding:0;list-style:none}
.footer__link{display:inline-block;font-size:.9rem;color:rgba(244,241,234,.78);border-bottom:1px solid transparent;padding-bottom:1px;transition:color .18s var(--ease),border-color .18s var(--ease)}
.footer__link:hover{color:#fff;border-bottom-color:var(--ochre)}
.footer__link--sm{font-size:.78rem}
.footer__plain{display:inline-block;font-size:.85rem;color:rgba(244,241,234,.72)}
.copybtn{display:inline-flex;align-items:center;gap:.5rem;font-family:var(--font-mono);font-size:.78rem;letter-spacing:.02em;color:rgba(244,241,234,.8);border-bottom:1px dashed rgba(244,241,234,.35);padding-bottom:1px;transition:color .18s var(--ease),border-color .18s var(--ease)}
.copybtn:hover{color:#fff;border-bottom-color:var(--ochre);border-bottom-style:solid}
.copybtn__hint{font-size:.64rem;letter-spacing:.12em;color:var(--lake-soft)}
.footer__bar{margin-top:clamp(28px,4vw,48px);background:rgba(0,0,0,.18);border-top:1px solid rgba(244,241,234,.16)}
.footer__bar-inner{display:flex;flex-wrap:wrap;align-items:center;justify-content:space-between;gap:.75rem 1.5rem;width:100%;max-width:var(--shell);margin-inline:auto;padding:1rem clamp(16px,4vw,40px)}
.footer__legal{font-family:var(--font-mono);font-size:.72rem;letter-spacing:.06em;color:rgba(244,241,234,.6)}
.footer__legal-list{display:flex;flex-wrap:wrap;gap:1.1rem;margin:0;padding:0;list-style:none}

@media (max-width:900px){
  .footer__inner{grid-template-columns:1fr 1fr}
  .footer__brand{grid-column:1 / -1}
}
@media (max-width:560px){
  .footer__inner{grid-template-columns:1fr}
  .footer__bar-inner{flex-direction:column;align-items:flex-start}
}

/* ---------- 10. 返回顶部 ---------- */
.totop{position:fixed;right:clamp(12px,3vw,28px);bottom:clamp(12px,3vw,28px);z-index:80;display:inline-flex;align-items:center;gap:.45em;padding:.55em .8em;background:var(--deep);color:var(--mist);border:1px solid rgba(244,241,234,.26);border-radius:var(--r);font-size:.74rem;letter-spacing:.12em;box-shadow:0 14px 30px -16px rgba(18,63,71,.85);opacity:0;transform:translateY(8px);pointer-events:none;transition:opacity .18s var(--ease),transform .18s var(--ease),background-color .18s var(--ease)}
.totop[data-visible="true"]{opacity:1;transform:none;pointer-events:auto}
.totop:hover{background:#0d3239}
.totop__icon{width:11px;height:11px;flex:0 0 auto}

/* ---------- 11. 入场显现（JS 开启 has-reveal 后才生效） ---------- */
.has-reveal [data-reveal]{opacity:0;transform:translateY(10px);transition:opacity .32s var(--ease),transform .32s var(--ease)}
.has-reveal [data-reveal].is-in{opacity:1;transform:none}

/* ---------- 12. 降级动效 ---------- */
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  *,*::before,*::after{animation-duration:.001ms!important;animation-iteration-count:1!important;transition-duration:.001ms!important}
  .has-reveal [data-reveal]{opacity:1;transform:none}
  .totop{transform:none}
}