:root{
  --ink:#000;
  --paper:#fff;
  --mute:#6b6b6b;
  --soft:#9a9a9a;
  --rule:#2a2a2a;
  --gap:clamp(1.25rem,4vw,3rem);
}
*,*::before,*::after{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{
  margin:0;
  padding-bottom:calc(78px + env(safe-area-inset-bottom));
  background:var(--paper);
  color:var(--ink);
  font-family:'Nunito Sans',system-ui,-apple-system,'PingFang SC','Hiragino Sans GB','Microsoft YaHei',sans-serif;
  font-size:1.0625rem;
  line-height:1.78;
  font-weight:400;
  overflow-x:hidden;
  font-variant-numeric:tabular-nums;
}
h1,h2,h3,h4{font-family:'Varela Round','Nunito Sans',system-ui,sans-serif;font-weight:900;line-height:1.02;letter-spacing:-.045em;margin:0}
p{margin:0 0 1.1em}
img{display:block;max-width:100%;height:auto}
a{color:inherit}
hr{border:0}

/* ---------- hero ---------- */
.hero{
  position:relative;
  display:flex;
  align-items:flex-end;
  min-height:100vh;
  min-height:100svh;
  padding:var(--gap);
  padding-bottom:clamp(3rem,9vh,6rem);
  background:#000;
  color:#fff;
  overflow:hidden;
}
.hero-media{position:absolute;inset:0;overflow:hidden}
.hero-media img{width:100%;height:100%;object-fit:cover;opacity:.5;filter:grayscale(1) contrast(1.2)}
.hero-media::after{
  content:"";
  position:absolute;
  inset:0;
  background:linear-gradient(180deg,rgba(0,0,0,.72),rgba(0,0,0,.18) 42%,rgba(0,0,0,.94));
}
.hero-inner{position:relative;z-index:2;width:100%;max-width:1600px;margin:0 auto}
.hero-badge{
  display:inline-block;
  border:1px solid #fff;
  padding:.35rem .9rem;
  font-size:.75rem;
  letter-spacing:.22em;
  margin:0 0 clamp(1rem,3vw,2rem);
  color:#fff;
}
.hero-title{
  font-size:clamp(2.6rem,10.5vw,11rem);
  line-height:.9;
  letter-spacing:-.055em;
  word-break:break-word;
  max-width:16ch;
}
.hero-desc{
  margin:clamp(1.2rem,3vw,2rem) 0 0;
  max-width:34rem;
  font-size:clamp(.95rem,1.6vw,1.15rem);
  line-height:1.7;
  color:#e8e8e8;
}
.hero-cue{
  margin:clamp(1.6rem,4vw,2.6rem) 0 0;
  font-size:.72rem;
  letter-spacing:.32em;
  color:var(--soft);
}
@keyframes rise{from{opacity:0;transform:translateY(30px)}to{opacity:1;transform:none}}
.hero-badge,.hero-title,.hero-desc,.hero-cue{animation:rise .9s cubic-bezier(.2,.7,.2,1) both}
.hero-title{animation-delay:.09s}
.hero-desc{animation-delay:.18s}
.hero-cue{animation-delay:.27s}

/* ---------- shell ---------- */
.shell{
  max-width:1600px;
  margin:0 auto;
  padding:0 var(--gap);
}
.side{
  border-bottom:1px solid var(--ink);
  padding:1.4rem 0;
}
.side-title{font-size:1rem;letter-spacing:-.02em}
.side hr{border-top:1px solid var(--ink);margin:.7rem 0 1rem}
.side-list{
  list-style:none;
  display:flex;
  gap:.45rem;
  margin:0;
  padding:0 0 .2rem;
  overflow-x:auto;
  scrollbar-width:none;
}
.side-list::-webkit-scrollbar{display:none}
.side-list li{flex:0 0 auto}
.side-list a{
  display:flex;
  align-items:center;
  min-height:42px;
  padding:.5rem .7rem;
  border:1px solid var(--ink);
  font-size:.85rem;
  text-decoration:none;
  white-space:nowrap;
  transition:background .18s ease,color .18s ease;
}
.side-list a:hover{background:var(--ink);color:var(--paper)}

/* ---------- section / content ---------- */
.doc{counter-reset:sec;padding-top:clamp(1.6rem,5vw,3rem)}
.doc > article{
  position:relative;
  padding:clamp(2.4rem,7vw,5.5rem) 0;
  border-top:1px solid var(--ink);
  scroll-margin-top:1.5rem;
}
.doc > article:first-child{border-top:0;padding-top:0}
.doc > article::before{
  counter-increment:sec;
  content:counter(sec,decimal-leading-zero);
  display:block;
  font-family:'Varela Round',sans-serif;
  font-size:.78rem;
  letter-spacing:.26em;
  margin-bottom:1rem;
  color:var(--mute);
}
.doc h2{
  font-size:clamp(1.9rem,6.2vw,4.2rem);
  line-height:.95;
  letter-spacing:-.05em;
  margin-bottom:.4rem;
  max-width:18ch;
}
.doc h3{
  font-size:clamp(1.25rem,3.4vw,1.85rem);
  margin:2rem 0 .4rem;
}
.doc h4{font-size:1.1rem;margin:1.6rem 0 .3rem;letter-spacing:-.02em}
.doc hr{border-top:2px solid var(--ink);margin:1.1rem 0 1.7rem}
.doc p,.doc li{max-width:68ch}
.doc ul,.doc ol{padding-left:1.25rem;margin:0 0 1.3em}
.doc li{margin-bottom:.5em}
.doc li::marker{font-weight:700}
.doc a{text-decoration:underline;text-decoration-thickness:2px;text-underline-offset:3px;transition:background .18s ease}
.doc a:hover{background:var(--ink);color:var(--paper);text-decoration-color:transparent}
.doc strong{font-weight:700}
.doc blockquote{
  margin:1.6rem 0;
  padding:.2rem 0 .2rem 1.2rem;
  border-left:4px solid var(--ink);
  font-size:1.05rem;
}
.doc img{margin:1.6rem 0;width:100%}
.doc figure{margin:1.6rem 0}
.doc table{width:100%;border-collapse:collapse;margin:1.4rem 0;font-size:.95rem}
.doc th,.doc td{border-bottom:1px solid var(--ink);padding:.6rem .5rem;text-align:left;vertical-align:top}
.doc code{
  font-family:ui-monospace,SFMono-Regular,Menlo,monospace;
  font-size:.9em;
  border:1px solid var(--ink);
  padding:.05em .35em;
}
.doc pre{overflow-x:auto;border:1px solid var(--ink);padding:1rem}
.doc pre code{border:0;padding:0}

/* ---------- footer ---------- */
.foot{
  background:#000;
  color:#fff;
  margin-top:clamp(2.5rem,8vw,6rem);
  padding:clamp(2.4rem,7vw,5rem) var(--gap) 0;
}
.foot-top{max-width:1600px;margin:0 auto}
.foot-brand{font-size:clamp(1.7rem,6vw,3.4rem);letter-spacing:-.05em}
.foot hr{border-top:1px solid var(--rule);margin:1.1rem 0 2rem}
.foot-cols{display:grid;grid-template-columns:1fr 1fr;gap:2rem 1.2rem}
.foot-form{grid-column:1 / -1}
.foot dt{font-size:.72rem;letter-spacing:.24em;color:var(--soft);margin-bottom:.5rem}
.foot dd{margin:0}
.foot dd a,.foot dd{
  display:inline-block;
  min-height:40px;
  padding:.45rem 0;
  font-size:.92rem;
  text-decoration:none;
  border-bottom:1px solid transparent;
  transition:border-color .18s ease;
}
.foot dd a:hover{border-bottom-color:#fff}
.sub{display:flex;flex-direction:column;gap:.6rem}
.sub-label{font-size:.72rem;letter-spacing:.24em;color:var(--soft)}
.sub-input{
  width:100%;
  min-height:46px;
  padding:.7rem .8rem;
  background:transparent;
  border:1px solid #fff;
  color:#fff;
  font:inherit;
  font-size:1rem;
}
.sub-input:focus{outline:2px solid #fff;outline-offset:2px}
.sub-btn{
  min-height:46px;
  padding:.7rem 1rem;
  background:#fff;
  color:#000;
  border:0;
  font:inherit;
  font-weight:700;
  cursor:pointer;
  transition:transform .18s ease;
}
.sub-btn:hover{transform:translateY(-2px)}
.foot-bottom{
  max-width:1600px;
  margin:2.4rem auto 0;
  border-top:1px solid var(--rule);
  padding:1.3rem 0 calc(1.3rem + env(safe-area-inset-bottom));
  font-size:.8rem;
  color:var(--soft);
}
.foot-bottom p{margin:0}

/* ---------- bottom nav ---------- */
.nav{
  position:fixed;
  left:0;
  right:0;
  bottom:0;
  z-index:60;
  display:flex;
  align-items:center;
  gap:.5rem;
  background:#000;
  color:#fff;
  border-top:1px solid var(--rule);
  padding:.4rem clamp(.7rem,3vw,1.5rem) calc(.4rem + env(safe-area-inset-bottom));
}
.nav-brand{
  flex:0 0 auto;
  padding:.7rem .1rem;
  font-family:'Varela Round',sans-serif;
  font-size:.92rem;
  letter-spacing:-.02em;
  color:#fff;
  text-decoration:none;
  white-space:nowrap;
}
.nav-list{display:none;list-style:none;margin:0;padding:0;gap:.1rem;flex:1 1 auto;min-width:0;overflow-x:auto;scrollbar-width:none}
.nav-list::-webkit-scrollbar{display:none}
.nav-list li{flex:0 0 auto}
.nav-list a{
  display:flex;
  align-items:center;
  min-height:44px;
  padding:.6rem .55rem;
  font-size:.85rem;
  color:#fff;
  text-decoration:none;
  white-space:nowrap;
  transition:background .16s ease,color .16s ease;
}
.nav-list a:hover{background:#fff;color:#000}
.nav-menu{position:relative;flex:0 0 auto}
.nav-menu summary{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:.6rem .85rem;
  border:1px solid #fff;
  font-size:.85rem;
  cursor:pointer;
  list-style:none;
}
.nav-menu summary::-webkit-details-marker{display:none}
.nav-panel{
  position:absolute;
  right:0;
  bottom:calc(100% + .7rem);
  min-width:min(70vw,300px);
  max-height:58vh;
  overflow:auto;
  background:#fff;
  color:#000;
  border:1px solid #000;
  padding:.8rem 1rem 1rem;
}
.nav-group{margin:0 0 .4rem;font-size:.7rem;letter-spacing:.24em;color:var(--mute)}
.nav-sub{list-style:none;margin:0;padding:0}
.nav-sub a{
  display:flex;
  align-items:center;
  min-height:44px;
  font-size:.9rem;
  text-decoration:none;
  border-bottom:1px solid #e4e4e4;
}
.nav-sub a:hover{background:#000;color:#fff}
.nav-cta{
  margin-left:auto;
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:.6rem .9rem;
  background:#fff;
  color:#000;
  font-size:.85rem;
  font-weight:700;
  text-decoration:none;
  white-space:nowrap;
  transition:transform .18s ease;
}
.nav-cta:hover{transform:translateY(-2px)}

/* ---------- reveal ---------- */
.js .reveal{opacity:0;transform:translateY(26px);transition:opacity .8s cubic-bezier(.2,.7,.2,1),transform .8s cubic-bezier(.2,.7,.2,1)}
.js .reveal.is-in{opacity:1;transform:none}

/* ---------- breakpoints ---------- */
@media (min-width:640px){
  .foot-cols{grid-template-columns:repeat(3,minmax(0,1fr))}
  .foot-form{grid-column:1 / -1}
  .sub{flex-direction:row;align-items:center;flex-wrap:wrap}
  .sub-label{width:100%}
  .sub-input{flex:1 1 14rem;width:auto}
  .sub-btn{flex:0 0 auto;padding:.7rem 1.6rem}
}
@media (min-width:900px){
  body{font-size:1.09rem}
  .shell{display:grid;grid-template-columns:minmax(150px,215px) minmax(0,1fr);gap:clamp(1.6rem,4vw,3.5rem);align-items:start}
  .side{
    position:sticky;
    top:2rem;
    border-bottom:0;
    border-right:1px solid var(--ink);
    padding:clamp(2rem,5vw,3rem) 1.4rem 2rem 0;
  }
  .side-list{display:block;overflow:visible;padding:0}
  .side-list li{display:block}
  .side-list a{
    display:flex;
    border:0;
    border-bottom:1px solid #e2e2e2;
    padding:.62rem 0;
    min-height:42px;
    font-size:.9rem;
  }
  .side-list a:hover{background:var(--ink);color:var(--paper);padding-left:.5rem}
  .doc{padding-top:clamp(2.4rem,5vw,3.6rem)}
  .doc > article:first-child{padding-top:0}
  .nav-list{display:flex}
  .nav-menu{display:none}
  .nav-brand{font-size:1rem;margin-right:.5rem}
  .foot-cols{grid-template-columns:repeat(4,minmax(0,1fr))}
  .foot-form{grid-column:auto}
  .sub{flex-direction:column;align-items:stretch}
  .sub-input{width:100%}
}
@media (min-width:1280px){
  .hero-title{max-width:14ch}
}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .hero-badge,.hero-title,.hero-desc,.hero-cue{animation:none}
  .js .reveal{opacity:1;transform:none;transition:none}
  .sub-btn:hover,.nav-cta:hover{transform:none}
}

button[aria-expanded]{min-width:44px;min-height:44px}