/* ==========================================================================
   baili-kaifu.com.cn — /assets/site.css
   共享外壳：reset / tokens / 头部 / 页脚 / 通用组件
   ========================================================================== */

/* ---------- 1. Tokens ---------- */
:root{
  --ink:#0B1B33;
  --ink-2:#14294A;
  --gold:#C9A227;
  --gold-2:#E8C86A;
  --jade:#2E7D6F;
  --cinnabar:#C0392B;
  --paper:#F4EFE4;
  --paper-2:#E7DFCE;
  --ink-black:#14171C;
  --haze:#8FA0B8;

  --line:rgba(201,162,39,.26);
  --line-strong:rgba(201,162,39,.62);

  --fg:var(--paper);
  --muted:var(--haze);
  --bg:var(--ink);
  --card-line:var(--line);
  --card-bg:var(--ink-2);

  --serif:"Noto Serif SC","Source Han Serif SC","Songti SC",Songti,STSong,Georgia,"Times New Roman",serif;
  --sans:"Inter","Noto Sans SC",-apple-system,BlinkMacSystemFont,"Segoe UI","PingFang SC","Hiragino Sans GB","Microsoft YaHei",sans-serif;
  --mono:"JetBrains Mono","IBM Plex Mono",ui-monospace,SFMono-Regular,Menlo,Consolas,monospace;

  --header-h:76px;
  --page-x:clamp(20px,4.6vw,72px);
  --surface-max:1680px;
  --gap:24px;
  --ease:200ms cubic-bezier(.22,.61,.36,1);
}

/* ---------- 2. Reset ---------- */
*,*::before,*::after{box-sizing:border-box;}
html{
  -webkit-text-size-adjust:100%;
  text-size-adjust:100%;
  scroll-behavior:smooth;
  scroll-padding-top:calc(var(--header-h) + 28px);
}
body,h1,h2,h3,h4,h5,p,figure,blockquote,dl,dd,ul,ol{margin:0;}
ul,ol{padding:0;list-style:none;}
img,svg,canvas{display:block;max-width:100%;height:auto;}
button,input,select,textarea{font:inherit;color:inherit;}
button{background:none;border:0;padding:0;cursor:pointer;}
a{color:inherit;text-decoration:none;}
[hidden]{display:none !important;}
table{border-collapse:collapse;width:100%;}

/* ---------- 3. Base ---------- */
body{
  min-height:100vh;
  font-family:var(--sans);
  font-size:16px;
  line-height:1.75;
  color:var(--fg);
  background-color:var(--ink);
  background-image:
    radial-gradient(1100px 620px at 10% -10%, rgba(46,125,111,.16), transparent 62%),
    radial-gradient(920px 540px at 94% 2%, rgba(192,57,43,.09), transparent 60%),
    radial-gradient(1500px 900px at 50% 118%, rgba(201,162,39,.08), transparent 70%);
  -webkit-font-smoothing:antialiased;
  overflow-x:hidden;
}
body[data-nav-open]{overflow:hidden;}

h1,h2,h3,h4,h5{
  font-family:var(--serif);
  font-weight:700;
  line-height:1.16;
  letter-spacing:-.01em;
  color:var(--fg);
}
h1{margin-bottom:.5em;}
h2{margin-bottom:.55em;}
h3{margin-bottom:.5em;}
p{margin-bottom:1em;}
p:last-child{margin-bottom:0;}

.display{
  font-family:var(--serif);
  font-weight:300;
  font-size:clamp(3rem,9vw,9rem);
  line-height:.94;
  letter-spacing:-.02em;
  color:var(--fg);
  word-break:break-word;
}
.num,.mono{
  font-family:var(--mono);
  font-variant-numeric:tabular-nums;
  font-feature-settings:"tnum" 1;
  letter-spacing:.02em;
}
.index-num,.eyebrow{
  font-family:var(--mono);
  font-size:12px;
  letter-spacing:.12em;
  line-height:1.5;
  color:var(--muted);
  text-transform:uppercase;
}
.footnote{
  font-size:13px;
  line-height:1.7;
  color:var(--muted);
}
.rule-gold{height:1px;border:0;background:var(--line);margin:0;}

:focus-visible{
  outline:2px solid var(--gold-2);
  outline-offset:3px;
  border-radius:1px;
}

.visually-hidden{
  position:absolute !important;
  width:1px;height:1px;
  padding:0;margin:-1px;
  overflow:hidden;
  clip:rect(0 0 0 0);
  white-space:nowrap;
  border:0;
}

/* ---------- 4. Skip link ---------- */
.skip-link{
  position:fixed;
  top:-90px;left:16px;
  z-index:900;
  padding:12px 20px;
  background:var(--gold);
  color:var(--ink-black);
  font-size:14px;
  letter-spacing:.1em;
  transition:top .18s ease;
}
.skip-link:focus{top:14px;}

/* ---------- 5. Header ---------- */
.site-header{
  position:fixed;
  top:0;left:0;right:0;
  z-index:400;
  background:transparent;
  border-bottom:1px solid transparent;
  transition:background-color .24s ease,border-color .24s ease;
}
.site-header[data-scrolled]{
  background:var(--ink);
  border-bottom-color:var(--line);
}
.site-header[data-open]{background:var(--ink);}

.site-header__bar{
  position:relative;
  z-index:2;
  display:flex;
  align-items:center;
  gap:clamp(14px,2.2vw,32px);
  width:100%;
  max-width:var(--surface-max);
  margin:0 auto;
  padding:0 var(--page-x);
  height:var(--header-h);
}

.brand{
  display:flex;
  flex-direction:column;
  gap:1px;
  flex:0 0 auto;
  line-height:1.15;
}
.brand__mark{
  font-family:var(--serif);
  font-weight:700;
  font-size:20px;
  letter-spacing:.08em;
  color:var(--paper);
}
.brand__sub{
  font-size:12px;
  letter-spacing:.12em;
  color:var(--haze);
}

.site-nav{margin-left:auto;}
.site-nav__list{
  display:flex;
  align-items:center;
  gap:clamp(10px,1.5vw,26px);
}
.site-nav__link{
  position:relative;
  display:inline-block;
  padding:8px 2px;
  font-size:14px;
  letter-spacing:.06em;
  color:rgba(244,239,228,.78);
  transition:color .18s ease;
  white-space:nowrap;
}
.site-nav__link::after{
  content:"";
  position:absolute;
  left:0;right:0;bottom:2px;
  height:1px;
  background:var(--gold);
  transform:scaleX(0);
  transform-origin:left center;
  transition:transform var(--ease);
}
.site-nav__link:hover{color:var(--paper);}
.site-nav__link:hover::after{transform:scaleX(1);}
.site-nav__link[aria-current="page"]{color:var(--gold-2);}
.site-nav__link[aria-current="page"]::after{
  transform:scaleX(1);
  background:var(--gold-2);
}

.header-status{
  display:flex;
  align-items:center;
  gap:9px;
  flex:0 0 auto;
  font-family:var(--mono);
  font-size:12px;
  letter-spacing:.1em;
  color:var(--haze);
  white-space:nowrap;
}
.status-dot{
  width:7px;height:7px;
  background:var(--jade);
  box-shadow:0 0 0 3px rgba(46,125,111,.2);
  animation:pulse-dot 6s ease-in-out infinite;
}
@keyframes pulse-dot{
  0%,100%{opacity:1;box-shadow:0 0 0 3px rgba(46,125,111,.2);}
  50%{opacity:.72;box-shadow:0 0 0 6px rgba(46,125,111,.06);}
}

.nav-toggle{
  display:none;
  position:relative;
  width:44px;height:44px;
  flex:0 0 auto;
  margin-left:auto;
  border:1px solid var(--line-strong);
  background:rgba(20,41,74,.72);
  transition:background-color .18s ease,border-color .18s ease;
}
.nav-toggle:hover{background:var(--ink-2);border-color:var(--gold);}
.nav-toggle__bar{
  position:absolute;
  left:11px;right:11px;
  height:1px;
  background:var(--gold-2);
  transition:transform .2s ease,opacity .2s ease;
}
.nav-toggle__bar:nth-child(1){top:16px;}
.nav-toggle__bar:nth-child(2){top:21.5px;}
.nav-toggle__bar:nth-child(3){top:27px;}
.site-header[data-open] .nav-toggle__bar:nth-child(1){transform:translateY(5.5px) rotate(45deg);}
.site-header[data-open] .nav-toggle__bar:nth-child(2){opacity:0;}
.site-header[data-open] .nav-toggle__bar:nth-child(3){transform:translateY(-5.5px) rotate(-45deg);}

.header-progress{
  position:absolute;
  left:0;right:0;bottom:0;
  height:1px;
  background:rgba(201,162,39,.14);
  opacity:0;
  transition:opacity .24s ease;
}
.site-header[data-scrolled] .header-progress{opacity:1;}
.header-progress__fill{
  display:block;
  height:100%;
  width:100%;
  background:linear-gradient(90deg,var(--jade),var(--gold) 46%,var(--gold-2));
  transform:scaleX(0);
  transform-origin:left center;
  transition:transform .12s linear;
}

@media (max-width:1024px){
  .header-status{display:none;}
  .site-nav__list{gap:12px;}
  .site-nav__link{font-size:13px;}
}

@media (max-width:900px){
  .nav-toggle{display:block;}
  .site-nav{
    position:fixed;
    inset:0;
    z-index:1;
    margin:0;
    padding:calc(var(--header-h) + 30px) var(--page-x) 48px;
    background:var(--ink);
    background-image:radial-gradient(760px 460px at 84% -4%, rgba(201,162,39,.14), transparent 62%);
    overflow-y:auto;
    opacity:0;
    visibility:hidden;
    transform:translateY(-10px);
    transition:opacity .2s ease,transform .2s ease,visibility .2s;
  }
  .site-header[data-open] .site-nav{
    opacity:1;
    visibility:visible;
    transform:translateY(0);
  }
  .site-nav__list{
    display:grid;
    grid-template-columns:repeat(2,minmax(0,1fr));
    gap:0 20px;
    border-top:1px solid var(--line);
  }
  .site-nav__item{border-bottom:1px solid var(--line);}
  .site-nav__link{
    display:block;
    padding:20px 2px;
    font-family:var(--serif);
    font-size:17px;
    letter-spacing:.04em;
    color:rgba(244,239,228,.86);
  }
  .site-nav__link::after{display:none;}
  .site-nav__link[aria-current="page"]{color:var(--gold-2);}
  .site-nav__link[aria-current="page"]::before{
    content:"№";
    font-family:var(--mono);
    font-size:11px;
    margin-right:8px;
    color:var(--gold);
  }
}

@media (max-width:520px){
  .brand__mark{font-size:17px;}
  .brand__sub{font-size:11px;letter-spacing:.08em;}
  .site-nav__list{grid-template-columns:1fr;}
}

/* ---------- 6. Footer ---------- */
.site-footer{
  position:relative;
  margin-top:0;
  padding:clamp(56px,7vw,104px) var(--page-x) 0;
  background:var(--ink);
  border-top:1px solid var(--line);
  color:var(--paper);
}
.site-footer::before{
  content:"";
  position:absolute;
  top:-1px;left:0;
  width:clamp(120px,18vw,260px);
  height:1px;
  background:var(--gold);
}

.footer-grid{
  width:100%;
  max-width:var(--surface-max);
  margin:0 auto;
  display:grid;
  grid-template-columns:1.5fr repeat(4,minmax(0,1fr));
  gap:clamp(28px,3vw,52px);
}
.footer-col{min-width:0;}
.footer-col--brand{display:flex;flex-direction:column;}

.footer-brand__name{
  font-family:var(--serif);
  font-weight:700;
  font-size:24px;
  letter-spacing:.1em;
  color:var(--paper);
  margin-bottom:8px;
}
.footer-brand__sub{
  font-size:12px;
  letter-spacing:.12em;
  color:var(--gold-2);
}
.footer-note{
  margin-top:18px;
  max-width:34em;
  font-size:13px;
  line-height:1.85;
  color:var(--haze);
}

.footer-col__title{
  font-family:var(--serif);
  font-size:15px;
  font-weight:700;
  letter-spacing:.08em;
  color:var(--gold-2);
  padding-bottom:12px;
  margin-bottom:16px;
  border-bottom:1px solid var(--line);
}
.footer-list{
  display:flex;
  flex-direction:column;
  gap:10px;
}
.footer-text,
.footer-link{
  font-size:13.5px;
  line-height:1.7;
  color:rgba(244,239,228,.72);
}
.footer-link{
  display:inline-block;
  transition:color .18s ease,transform .18s ease;
}
.footer-link:hover{
  color:var(--gold-2);
  transform:translateX(3px);
}
.footer-list .num{color:var(--gold-2);font-size:12.5px;}

.footer-bottom{
  width:100%;
  max-width:var(--surface-max);
  margin:clamp(44px,5vw,80px) auto 0;
  padding:22px 0 34px;
  border-top:1px solid var(--line);
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  justify-content:space-between;
  gap:12px 32px;
}
.footer-legal,
.footer-credit{
  font-size:12px;
  letter-spacing:.08em;
  line-height:1.8;
  color:var(--haze);
  margin:0;
}
.footer-credit .num{color:var(--gold-2);}

@media (max-width:1180px){
  .footer-grid{grid-template-columns:repeat(3,minmax(0,1fr));}
  .footer-col--brand{grid-column:1 / -1;}
}
@media (max-width:720px){
  .footer-grid{grid-template-columns:minmax(0,1fr);}
  .footer-bottom{flex-direction:column;align-items:flex-start;}
}

/* ---------- 7. Layout primitives ---------- */
.container{
  width:100%;
  max-width:var(--surface-max);
  margin-inline:auto;
  padding-inline:var(--page-x);
}
.main-offset{padding-top:var(--header-h);}
.section{padding-block:clamp(56px,7vw,112px);}
.section--tight{padding-block:clamp(32px,4vw,60px);}

.surface--dark{background:var(--ink);color:var(--paper);}
.surface--panel{
  background:var(--ink-2);
  color:var(--paper);
  border-block:1px solid var(--line);
}
.surface--light{
  --fg:var(--ink-black);
  --muted:#5A6B7E;
  --card-line:rgba(11,27,51,.16);
  --card-bg:#FBF8F1;
  background:var(--paper);
  background-image:radial-gradient(900px 520px at 88% 0%, rgba(201,162,39,.12), transparent 66%);
  color:var(--ink-black);
}
.surface--light .panel__meta,
.surface--light .index-num,
.surface--light .eyebrow,
.surface--light .footnote{color:#5A6B7E;}

.page-shell{
  width:100%;
  max-width:var(--surface-max);
  margin-inline:auto;
  padding-inline:var(--page-x);
  display:grid;
  grid-template-columns:240px minmax(0,1fr);
  gap:clamp(24px,3vw,48px);
  align-items:start;
}
@media (max-width:1024px){
  .page-shell{grid-template-columns:minmax(0,1fr);}
}

/* ---------- 8. Rail (厅别 / 章节索引) ---------- */
.rail{
  position:sticky;
  top:calc(var(--header-h) + 28px);
  align-self:start;
  max-height:calc(100vh - var(--header-h) - 56px);
  overflow-y:auto;
  padding-right:6px;
}
.rail__title{
  font-family:var(--mono);
  font-size:12px;
  letter-spacing:.14em;
  color:var(--muted);
  padding-bottom:10px;
  margin-bottom:12px;
  border-bottom:1px solid var(--line);
}
.rail__list{display:flex;flex-direction:column;}
.rail__link{
  position:relative;
  display:block;
  padding:9px 0 9px 16px;
  font-size:13px;
  line-height:1.5;
  color:rgba(244,239,228,.68);
  border-left:1px solid var(--line);
  transition:color .18s ease,padding-left .18s ease;
}
.rail__link::before{
  content:"";
  position:absolute;
  left:-1px;top:0;bottom:0;
  width:1px;
  background:var(--gold-2);
  transform:scaleY(0);
  transform-origin:top center;
  transition:transform var(--ease);
}
.rail__link:hover{color:var(--paper);}
.rail__link[aria-current="true"]{
  color:var(--gold-2);
  padding-left:20px;
}
.rail__link[aria-current="true"]::before{transform:scaleY(1);}
.surface--light .rail__link{color:rgba(20,23,28,.62);}
.surface--light .rail__link:hover{color:var(--ink-black);}

@media (max-width:1024px){
  .rail{
    position:static;
    max-height:none;
    overflow:visible;
  }
  .rail__list{
    flex-direction:row;
    flex-wrap:wrap;
    gap:8px;
  }
  .rail__link{
    border:1px solid var(--line);
    padding:7px 12px;
  }
  .rail__link::before{display:none;}
  .rail__link[aria-current="true"]{padding-left:12px;border-color:var(--gold);}
}

/* ---------- 9. Grid ---------- */
.grid{display:grid;gap:var(--gap);}
.grid--2{grid-template-columns:repeat(2,minmax(0,1fr));}
.grid--3{grid-template-columns:repeat(3,minmax(0,1fr));}
.grid--4{grid-template-columns:repeat(4,minmax(0,1fr));}
.grid--auto{grid-template-columns:repeat(auto-fit,minmax(240px,1fr));}
@media (max-width:960px){
  .grid--3,.grid--4{grid-template-columns:repeat(2,minmax(0,1fr));}
}
@media (max-width:640px){
  .grid--2,.grid--3,.grid--4,.grid--auto{grid-template-columns:minmax(0,1fr);}
}

/* ---------- 10. Bento ---------- */
.bento{
  display:grid;
  grid-template-columns:repeat(12,minmax(0,1fr));
  gap:var(--gap);
  grid-auto-rows:minmax(96px,auto);
}
.bento__cell{
  position:relative;
  display:flex;
  flex-direction:column;
  justify-content:space-between;
  gap:14px;
  min-width:0;
  padding:clamp(18px,2vw,28px);
  background:var(--card-bg);
  border:1px solid var(--card-line);
  transition:border-color .2s ease,background-color .2s ease;
}
.bento__cell:hover{border-color:var(--line-strong);}
.bento--focus{
  grid-column:span 6;
  grid-row:span 2;
  background:linear-gradient(152deg,#17305A 0%,#0C1E3A 68%,#0B1B33 100%);
  border-color:var(--line-strong);
}
.bento__label{
  font-family:var(--mono);
  font-size:12px;
  letter-spacing:.12em;
  color:var(--muted);
}
.bento__value{
  font-family:var(--serif);
  font-weight:300;
  font-size:clamp(2rem,4.4vw,3.6rem);
  line-height:1;
  letter-spacing:-.02em;
  color:var(--fg);
}
@media (max-width:900px){
  .bento{grid-template-columns:repeat(6,minmax(0,1fr));}
  .bento--focus{grid-column:span 6;grid-row:span 1;}
}
@media (max-width:600px){
  .bento{grid-template-columns:minmax(0,1fr);grid-auto-rows:auto;}
  .bento--focus{grid-column:auto;}
}

.cut-corner::after{
  content:"";
  position:absolute;
  left:0;top:0;
  width:26px;height:26px;
  pointer-events:none;
  background:linear-gradient(45deg,transparent calc(50% - .5px),var(--gold) calc(50% - .5px),var(--gold) calc(50% + .5px),transparent calc(50% + .5px));
}

/* ---------- 11. Panel ---------- */
.panel{
  background:var(--card-bg);
  border:1px solid var(--card-line);
}
.panel__head{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:16px;
  flex-wrap:wrap;
  padding:16px 20px;
  border-bottom:1px solid var(--card-line);
}
.panel__title{
  font-family:var(--serif);
  font-size:17px;
  font-weight:700;
  letter-spacing:.04em;
  color:var(--fg);
  margin:0;
}
.panel__meta{
  font-family:var(--mono);
  font-size:12px;
  letter-spacing:.08em;
  color:var(--muted);
}
.panel__body{padding:clamp(16px,2vw,26px);}

/* ---------- 12. Tags & buttons ---------- */
.tag{
  display:inline-flex;
  align-items:center;
  gap:6px;
  padding:4px 10px;
  font-family:var(--mono);
  font-size:11px;
  letter-spacing:.1em;
  border:1px solid var(--line-strong);
  color:var(--gold-2);
  white-space:nowrap;
}
.tag--jade{border-color:rgba(46,125,111,.78);color:#79C9B7;}
.tag--cinnabar{border-color:rgba(192,57,43,.8);color:#E4796B;}
.tag--gold{border-color:var(--gold);background:rgba(201,162,39,.12);color:var(--gold-2);}

.btn{
  display:inline-flex;
  align-items:center;
  justify-content:center;
  gap:10px;
  padding:13px 26px;
  font-family:var(--sans);
  font-size:14px;
  letter-spacing:.1em;
  color:var(--gold-2);
  background:transparent;
  border:1px solid var(--gold);
  transition:background-color .2s ease,color .2s ease,border-color .2s ease;
}
.btn:hover{background:var(--gold);color:var(--ink);}
.btn--solid{background:var(--gold);color:var(--ink);}
.btn--solid:hover{background:var(--gold-2);border-color:var(--gold-2);color:var(--ink);}
.btn--jade{border-color:var(--jade);color:#7FD3C2;}
.btn--jade:hover{background:var(--jade);color:var(--paper);}

/* ---------- 13. Breadcrumb ---------- */
.breadcrumb{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  gap:8px;
  font-family:var(--mono);
  font-size:12px;
  letter-spacing:.1em;
  color:var(--muted);
}
.breadcrumb__link{
  color:var(--muted);
  transition:color .18s ease;
}
.breadcrumb__link:hover{color:var(--gold-2);}
.breadcrumb__sep{color:var(--line-strong);}
.surface--light .breadcrumb__link:hover{color:var(--ink-black);}

/* ---------- 14. Media containers ---------- */
.media{
  position:relative;
  display:block;
  width:100%;
  overflow:hidden;
  background:linear-gradient(140deg,#132746 0%,#0A1830 100%);
  border:1px solid var(--card-line);
}
.media__img{
  width:100%;
  height:100%;
  object-fit:cover;
  display:block;
}
.media__placeholder{
  display:flex;
  align-items:center;
  justify-content:center;
  width:100%;
  height:100%;
  padding:20px;
  text-align:center;
  font-family:var(--mono);
  font-size:12px;
  letter-spacing:.12em;
  color:var(--haze);
  background-image:
    repeating-linear-gradient(0deg,rgba(201,162,39,.07) 0 1px,transparent 1px 32px),
    repeating-linear-gradient(90deg,rgba(201,162,39,.07) 0 1px,transparent 1px 32px);
}
.media__caption{
  position:absolute;
  left:0;right:0;bottom:0;
  padding:12px 16px;
  font-family:var(--mono);
  font-size:12px;
  letter-spacing:.08em;
  color:var(--paper);
  background:linear-gradient(to top,rgba(11,27,51,.94),rgba(11,27,51,0));
}
.media--16x9{aspect-ratio:16 / 9;}
.media--4x3{aspect-ratio:4 / 3;}
.media--1x1{aspect-ratio:1 / 1;}
.media--tall{aspect-ratio:3 / 4;}
@media (max-width:640px){
  .media--tall{aspect-ratio:4 / 5;}
}

/* ---------- 15. Disclosure ---------- */
.disclosure{
  border:1px solid var(--card-line);
  background:var(--card-bg);
}
.disclosure__trigger{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:16px;
  width:100%;
  padding:16px 20px;
  text-align:left;
  font-family:var(--serif);
  font-size:16px;
  font-weight:700;
  letter-spacing:.03em;
  color:var(--fg);
  border-bottom:1px solid transparent;
  transition:color .18s ease,border-color .18s ease,background-color .18s ease;
}
.disclosure__trigger:hover{color:var(--gold-2);background:rgba(201,162,39,.06);}
.disclosure__trigger[aria-expanded="true"]{border-bottom-color:var(--card-line);}
.disclosure__trigger::after{
  content:"＋";
  font-family:var(--mono);
  font-size:14px;
  color:var(--gold);
  flex:0 0 auto;
}
.disclosure__trigger[aria-expanded="true"]::after{content:"－";}
.disclosure__panel{
  padding:16px 20px 20px;
  font-size:15px;
  line-height:1.8;
  color:var(--muted);
  animation:panel-in .2s ease both;
}
@keyframes panel-in{
  from{opacity:0;transform:translateY(-4px);}
  to{opacity:1;transform:none;}
}

/* ---------- 16. Back to top ---------- */
.to-top{
  position:fixed;
  right:clamp(16px,3vw,34px);
  bottom:clamp(16px,3vw,34px);
  z-index:350;
  opacity:0;
  visibility:hidden;
  transform:translateY(12px);
  transition:opacity .24s ease,transform .24s ease,visibility .24s;
}
.to-top[data-visible]{
  opacity:1;
  visibility:visible;
  transform:none;
}
.to-top__btn{
  display:flex;
  flex-direction:column;
  align-items:center;
  justify-content:center;
  gap:2px;
  width:52px;height:52px;
  font-family:var(--mono);
  font-size:14px;
  line-height:1;
  color:var(--gold-2);
  background:var(--ink-2);
  border:1px solid var(--gold);
  transition:background-color .2s ease,color .2s ease;
}
.to-top__btn:hover{background:var(--gold);color:var(--ink);}
.to-top__label{
  font-size:10px;
  letter-spacing:.12em;
}
@media (max-width:640px){
  .to-top__btn{width:46px;height:46px;}
}

/* ---------- 17. Reduced motion ---------- */
@media (prefers-reduced-motion: reduce){
  html{scroll-behavior:auto;}
  *,*::before,*::after{
    animation-duration:.001ms !important;
    animation-iteration-count:1 !important;
    transition-duration:.001ms !important;
    scroll-behavior:auto !important;
  }
  .header-progress__fill{transition:none;}
  .status-dot{animation:none;}
}