:root{
  --ink:#000;
  --paper:#fff;
  --r:10px;
  --pad:clamp(1.1rem,4vw,2.5rem);
  --max:1200px;
}
*,*::before,*::after{box-sizing:border-box}
html{
  font-size:16px;
  scroll-behavior:smooth;
  scroll-padding-top:10rem;
  -webkit-text-size-adjust:100%;
}
body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:"Manrope","Helvetica Neue",Arial,"PingFang SC","Microsoft YaHei",sans-serif;
  font-size:1rem;
  line-height:1.65;
  -webkit-font-smoothing:antialiased;
}
img{max-width:100%;height:auto}
button,input{font:inherit;color:inherit}
h1,h2,h3{
  font-family:"Syne","Manrope","PingFang SC","Microsoft YaHei",sans-serif;
  font-weight:700;
  line-height:1.06;
  letter-spacing:-.02em;
}
a{color:inherit}
:focus-visible{outline:2px solid var(--ink);outline-offset:3px}

/* 页头：品牌行 + 菜单行 */
.site-head{
  position:sticky;
  top:0;
  z-index:40;
  background:var(--paper);
  border-bottom:1px solid var(--ink);
}
.head-row{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:1rem;
  max-width:var(--max);
  margin:0 auto;
  padding:.55rem var(--pad);
}
.brand{
  display:inline-flex;
  align-items:center;
  gap:.55rem;
  min-height:44px;
  text-decoration:none;
  font-family:"Syne","Manrope",sans-serif;
  font-weight:700;
  font-size:1.0625rem;
  letter-spacing:-.01em;
}
.brand-logo{display:block;width:26px;height:26px;object-fit:contain}
.head-acts{display:flex;align-items:center;gap:.5rem}
.head-cta{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:0 .85rem;
  border:1px solid var(--ink);
  background:var(--paper);
  text-decoration:none;
  font-size:1rem;
  transition:background .2s ease,color .2s ease;
}
.head-cta:hover{background:var(--ink);color:var(--paper)}
.burger{
  position:relative;
  z-index:60;
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:0 .95rem;
  background:var(--ink);
  color:var(--paper);
  border:1px solid var(--ink);
  cursor:pointer;
  font-size:1rem;
  letter-spacing:.04em;
  transition:background .2s ease,color .2s ease;
}
.burger:hover{background:var(--paper);color:var(--ink)}
.site-nav{
  max-width:var(--max);
  margin:0 auto;
  padding:.1rem var(--pad) .5rem;
}
.site-nav > p{
  display:flex;
  flex-wrap:wrap;
  gap:0 1.15rem;
  margin:0;
}
.site-nav a{
  display:inline-flex;
  align-items:center;
  min-height:40px;
  font-size:1rem;
  text-decoration:none;
  border-bottom:1px solid transparent;
  transition:border-color .2s ease;
}
.site-nav a:hover{border-bottom-color:var(--ink)}

/* 全屏遮罩菜单 */
body.menu-open{overflow:hidden}
body.menu-open .site-nav{
  position:fixed;
  inset:0;
  z-index:50;
  display:flex;
  align-items:center;
  justify-content:center;
  max-width:none;
  margin:0;
  padding:5rem 1.5rem;
  overflow-y:auto;
  background:var(--ink);
}
body.menu-open .site-nav > p{
  display:grid;
  gap:0;
  width:min(560px,100%);
}
body.menu-open .site-nav a{
  color:var(--paper);
  border-bottom:1px solid rgba(255,255,255,.35);
  font-family:"Syne","Manrope",sans-serif;
  font-size:clamp(1.25rem,4.4vw,1.9rem);
  min-height:60px;
}
body.menu-open .burger{
  position:fixed;
  top:.65rem;
  right:var(--pad);
  background:var(--paper);
  color:var(--ink);
}

/* 主区网格：正文左、侧栏右 */
main{
  display:grid;
  grid-template-columns:minmax(0,1fr) 300px;
  gap:0 3rem;
  max-width:var(--max);
  margin:0 auto;
  padding:0 var(--pad);
}
main > div{
  grid-column:1;
  min-width:0;
  padding:3rem 0;
  border-top:1px solid var(--ink);
}
main > div:first-child{border-top:0}

/* 首屏 */
.hero{
  grid-column:1 / -1;
  display:grid;
  grid-template-rows:auto 1fr;
  min-height:100svh;
  padding-top:clamp(2rem,7vw,5rem);
  border-top:0;
}
.hero-title{
  font-size:clamp(2.3rem,8.5vw,6.5rem);
  line-height:.92;
  letter-spacing:-.045em;
  margin:0;
  max-width:16ch;
  word-break:break-word;
}
.hero-cut{
  align-self:end;
  width:100%;
  height:clamp(110px,24vh,240px);
  margin:clamp(2rem,6vw,4rem) 0 0;
  background:var(--ink);
  clip-path:polygon(0 100%,100% 0,100% 100%);
}

/* 侧栏 */
.rail{
  grid-column:2;
  grid-row:2 / span 40;
  align-self:start;
  position:sticky;
  top:9rem;
  padding-top:3rem;
  border-top:1px solid var(--ink);
}
.toc{
  border:1px solid var(--ink);
  border-radius:var(--r);
  padding:1.15rem;
  background:var(--paper);
  box-shadow:0 10px 24px rgba(0,0,0,.07);
}
.toc .eyebrow{
  display:block;
  font-size:1rem;
  letter-spacing:.2em;
  margin:0 0 .4rem;
}
.toc-h{font-size:1.3rem;margin:0 0 1rem}
.toc-list{
  list-style:none;
  margin:0;
  padding:0;
  counter-reset:t;
}
.toc-list li{counter-increment:t}
.toc-list a{
  display:flex;
  align-items:center;
  gap:.6rem;
  min-height:44px;
  text-decoration:none;
  border-top:1px solid var(--ink);
  transition:padding-left .2s ease;
}
.toc-list a::before{
  content:counter(t,decimal-leading-zero);
  font-family:"Syne","Manrope",sans-serif;
  font-size:1rem;
  letter-spacing:.04em;
}
.toc-list a:hover{padding-left:.45rem}

/* 正文排版 */
main > div:not(.hero):not(.rail) h2{
  font-size:clamp(1.5rem,3.4vw,2.2rem);
  margin:0 0 1rem;
}
main > div:not(.hero):not(.rail) h3{
  font-size:clamp(1.2rem,2.4vw,1.5rem);
  margin:1.7rem 0 .6rem;
}
main > div p{margin:0 0 1.1rem;line-height:1.75;max-width:68ch}
main > div ul,
main > div ol{margin:0 0 1.1rem;padding-left:1.35rem;line-height:1.7;max-width:68ch}
main > div li{margin:.35rem 0}
main > div a{
  text-decoration:underline;
  text-underline-offset:.18em;
  transition:background .2s ease,color .2s ease;
}
main > div a:hover{background:var(--ink);color:var(--paper);text-decoration:none}
main > div small{
  display:block;
  font-size:1rem;
  letter-spacing:.2em;
  margin-bottom:.5rem;
}
main > div figure{margin:1.6rem 0}
main > div figcaption{font-size:1rem;margin-top:.5rem;letter-spacing:.04em}
main > div img{border-radius:var(--r);display:block}
main > div blockquote{
  margin:1.6rem 0;
  padding-left:1.1rem;
  border-left:3px solid var(--ink);
  font-size:1.0625rem;
}
main > div strong{font-weight:700}
main > div hr{border:0;border-top:1px solid var(--ink);margin:2rem 0}

/* 页脚 */
.site-foot{
  margin-top:3rem;
  padding:2.5rem 0 2rem;
  border-top:1px solid var(--ink);
}
.foot-in{max-width:var(--max);margin:0 auto;padding:0 var(--pad)}
.foot-grid{
  display:grid;
  grid-template-columns:1.5fr 1fr 1fr 1.5fr;
  gap:2rem;
}
.foot-col h3{
  font-size:1rem;
  letter-spacing:.2em;
  font-weight:700;
  margin:0 0 .9rem;
}
.foot-col ul{list-style:none;margin:0;padding:0}
.foot-col li a{
  display:inline-flex;
  align-items:center;
  min-height:40px;
  font-size:1rem;
  text-decoration:none;
  border-bottom:1px solid transparent;
  transition:border-color .2s ease;
}
.foot-col li a:hover{border-bottom-color:var(--ink)}
.foot-addr{margin:0;font-style:normal}
.foot-addr a{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  font-family:"Syne","Manrope",sans-serif;
  font-weight:700;
  font-size:1.1rem;
  text-decoration:none;
}
.sub{display:flex;gap:.5rem;flex-wrap:wrap}
.sub-in{
  flex:1 1 8rem;
  min-height:44px;
  padding:0 .8rem;
  border:1px solid var(--ink);
  border-radius:var(--r);
  background:var(--paper);
  font-size:1rem;
}
.sub-btn{
  min-height:44px;
  padding:0 1.1rem;
  border:1px solid var(--ink);
  border-radius:var(--r);
  background:var(--ink);
  color:var(--paper);
  cursor:pointer;
  font-size:1rem;
  transition:background .2s ease,color .2s ease;
}
.sub-btn:hover{background:var(--paper);color:var(--ink)}
.foot-legal{
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  justify-content:center;
  gap:.5rem 1.5rem;
  margin:2.5rem 0 0;
  padding-top:1.25rem;
  border-top:1px solid var(--ink);
  font-size:1rem;
  text-align:center;
}
.foot-legal a{
  display:inline-flex;
  align-items:center;
  min-height:40px;
  text-decoration:none;
  border-bottom:1px solid transparent;
}
.foot-legal a:hover{border-bottom-color:var(--ink)}

/* 滚动入场 */
.js .reveal{
  opacity:0;
  transform:translateY(16px);
  transition:opacity .5s ease,transform .5s ease;
}
.js .reveal.is-in{opacity:1;transform:none}

@media (max-width:900px){
  main{grid-template-columns:minmax(0,1fr);gap:0}
  .rail{
    grid-column:1;
    grid-row:auto;
    position:static;
    padding-top:3rem;
  }
  .hero{min-height:auto;padding-bottom:2rem}
  .hero-title{font-size:clamp(2.2rem,11vw,3.6rem)}
  .hero-cut{height:clamp(90px,16vh,160px)}
  .foot-grid{grid-template-columns:1fr 1fr}
}
@media (max-width:560px){
  html{scroll-padding-top:12rem}
  .brand-txt{font-size:1rem}
  .head-cta{padding:0 .6rem}
  .foot-grid{grid-template-columns:1fr;gap:1.5rem}
}
@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .js .reveal{opacity:1;transform:none;transition:none}
}

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