@import url('https://fonts.googleapis.com/css2?family=Space+Grotesk:wght@400;500;600;700&display=swap');

:root{
  --ink:#172623;
  --mint:#5cc6b0;
  --sand:#d4c4a8;
  --clay:#c67b5c;
  --paper:#f2ebdd;
  --paper2:#e7dcc8;
  --line:rgba(23,38,35,.16);
  --rail:268px;
  --r:4px;
}

*{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{
  margin:0;
  background:var(--paper);
  color:var(--ink);
  font-family:'Space Grotesk',system-ui,-apple-system,'Segoe UI','PingFang SC','Hiragino Sans GB','Microsoft YaHei',sans-serif;
  font-size:17px;
  line-height:1.65;
  overflow-x:hidden;
}
img{max-width:100%}
a{color:inherit}
a:focus-visible,button:focus-visible{outline:3px solid var(--clay);outline-offset:2px}

body::before{
  content:"";
  position:fixed;
  inset:0;
  z-index:9;
  pointer-events:none;
  opacity:.26;
  background-image:url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='140' height='140'%3E%3Cfilter id='g'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='140' height='140' filter='url(%23g)' opacity='0.32'/%3E%3C/svg%3E");
}

/* 左侧竖排栏 */
.rail{
  position:fixed;
  inset:0 auto 0 0;
  z-index:3;
  width:var(--rail);
  padding:26px 20px 24px;
  display:flex;
  flex-direction:column;
  gap:14px;
  border-right:3px solid var(--ink);
  background:linear-gradient(180deg,var(--sand) 0%,#e3d5bd 48%,var(--paper2) 100%);
}
.brand{
  align-self:flex-start;
  display:inline-block;
  padding:2px 0 6px;
  font-size:20px;
  font-weight:700;
  letter-spacing:.05em;
  text-decoration:none;
  border-bottom:3px solid var(--ink);
}
.rail-nav{min-width:0}
.menu{
  list-style:none;
  margin:0;
  padding:0;
  display:flex;
  flex-direction:column;
  gap:2px;
}
.mi a,.grp-btn{
  display:block;
  width:100%;
  min-height:44px;
  padding:12px 10px 12px 14px;
  font:inherit;
  font-size:16px;
  font-weight:600;
  text-align:left;
  text-decoration:none;
  color:var(--ink);
  background:transparent;
  border:0;
  border-left:3px solid transparent;
  border-radius:0 var(--r) var(--r) 0;
  cursor:pointer;
  transition:background .25s ease-out,border-color .25s ease-out;
}
.mi a:hover,.grp-btn:hover,.mi a:focus-visible,.grp-btn:focus-visible{
  background:rgba(92,198,176,.3);
  border-left-color:var(--ink);
}
.mi:first-child a{background:var(--ink);color:var(--paper);border-left-color:var(--mint)}
.grp>.sub{
  list-style:none;
  margin:0 0 0 14px;
  padding:0 0 0 10px;
  max-height:0;
  overflow:hidden;
  border-left:1px dashed rgba(23,38,35,.32);
  transition:max-height .35s ease-out;
}
.grp:hover>.sub,.grp:focus-within>.sub,.grp.open>.sub{max-height:320px}
.sub a{
  display:block;
  min-height:42px;
  padding:9px 10px;
  font-size:16px;
  text-decoration:none;
  border-radius:var(--r);
}
.sub a:hover{background:rgba(92,198,176,.24)}
.callout{
  margin-top:auto;
  display:flex;
  align-items:center;
  justify-content:center;
  min-height:48px;
  padding:12px;
  background:var(--ink);
  color:var(--mint);
  font-weight:700;
  letter-spacing:.08em;
  text-decoration:none;
  border-radius:var(--r);
  transition:background .25s ease-out,transform .25s ease-out;
}
.callout:hover{background:#22403a;transform:translateY(-1px)}

/* 主区 */
main{margin-left:var(--rail);min-width:0}
.stage{max-width:980px;margin:0 auto;padding:0 34px 70px}

.hero{
  min-height:44vh;
  display:flex;
  flex-direction:column;
  justify-content:flex-end;
  text-align:right;
  padding-bottom:26px;
}
.hero-band{
  display:block;
  height:15px;
  margin-bottom:auto;
  background:linear-gradient(96deg,var(--mint) 0 58%,var(--clay) 58% 100%);
  clip-path:polygon(0 0,100% 0,100% 38%,0 100%);
}
.hero h1{
  margin:26px 0 0;
  font-size:clamp(29px,5.2vw,54px);
  line-height:1.08;
  font-weight:700;
  letter-spacing:-.015em;
}
.hero-figure{margin:22px 0 0}
.hero-figure img{
  display:block;
  width:100%;
  height:auto;
  clip-path:polygon(0 22px,100% 0,100% 100%,0 100%);
}

/* 正文 */
.stage>div{padding:30px 0;border-top:1px solid var(--line);scroll-margin-top:20px}
.stage h2{margin:0 0 12px;font-size:clamp(20px,2.5vw,26px);line-height:1.25;letter-spacing:.01em}
.stage>div.band{
  display:grid;
  grid-template-columns:minmax(0,.85fr) minmax(0,1.15fr);
  gap:26px;
  align-items:end;
  padding:26px 0 24px;
  border-top:3px solid var(--ink);
}
.band h2{margin:0;font-size:clamp(21px,2.9vw,30px);line-height:1.15}
.subtitle{margin:0;font-size:16px;color:rgba(23,38,35,.72)}
.stage h3{margin:24px 0 8px;font-size:18px;line-height:1.4}
.stage p{margin:0 0 14px}
.stage ul,.stage ol{margin:0 0 14px;padding-left:22px}
.stage li{margin:6px 0}
.stage a{color:#1f6b5b;text-decoration:underline;text-underline-offset:3px}
.stage a:hover{color:#134a3f}
.stage img{display:block;margin:16px 0;height:auto;border-radius:var(--r)}
.stage blockquote{
  margin:18px 0;
  padding:14px 18px;
  background:var(--paper2);
  border-left:4px solid var(--clay);
  border-radius:var(--r);
}
.stage blockquote p:last-child{margin:0}
.stage table{
  display:block;
  width:100%;
  overflow-x:auto;
  border-collapse:collapse;
  font-size:16px;
}
.stage th,.stage td{padding:8px 10px;border-bottom:1px solid var(--line);text-align:left}
.stage code{font-size:16px;background:var(--paper2);padding:1px 5px;border-radius:3px}

/* 页脚 */
.foot{
  margin-left:var(--rail);
  display:grid;
  grid-template-columns:1.5fr .85fr .95fr .85fr;
  gap:26px;
  padding:48px 34px 26px;
  background:var(--ink);
  color:var(--paper);
}
.foot div{min-width:0}
.foot h2{
  margin:0 0 12px;
  font-size:16px;
  font-weight:600;
  letter-spacing:.14em;
  color:var(--sand);
}
.foot-mark{
  margin:0;
  font-size:clamp(34px,4.6vw,62px);
  line-height:.95;
  font-weight:700;
  letter-spacing:-.02em;
  color:var(--mint);
}
.foot ul{list-style:none;margin:0;padding:0}
.foot li a{
  display:block;
  min-height:42px;
  padding:9px 0;
  font-size:16px;
  text-decoration:none;
  color:var(--paper);
  border-bottom:1px solid rgba(212,196,168,.18);
}
.foot li a:hover{color:var(--mint)}
.foot-call{
  display:inline-flex;
  align-items:center;
  min-height:44px;
  padding:11px 16px;
  background:var(--mint);
  color:var(--ink);
  font-weight:700;
  text-decoration:none;
  border-radius:var(--r);
}
.foot-call:hover{background:#7ad6c4}
.copy{margin:0;font-size:16px;color:var(--sand)}

/* 动效 */
.rv{opacity:0;transform:translateY(16px)}
.rv.in{opacity:1;transform:none;transition:opacity .55s ease-out,transform .55s ease-out}

@keyframes railIn{
  from{opacity:0;transform:translateX(-12px)}
  to{opacity:1;transform:none}
}
.menu>li{animation:railIn .45s ease-out backwards}
.menu>li:nth-child(1){animation-delay:.03s}
.menu>li:nth-child(2){animation-delay:.09s}
.menu>li:nth-child(3){animation-delay:.15s}
.rail .brand,.rail .callout{animation:railIn .45s ease-out backwards}
.rail .callout{animation-delay:.2s}

@media (max-width:880px){
  .rail{
    position:static;
    width:auto;
    display:block;
    padding:14px 16px 12px;
    border-right:0;
    border-bottom:3px solid var(--ink);
  }
  .brand{font-size:18px;padding-bottom:4px;border-bottom-width:2px;margin-bottom:10px}
  .menu{
    flex-direction:row;
    gap:8px;
    overflow-x:auto;
    padding:2px 0 6px;
    scrollbar-width:thin;
  }
  .menu>li{flex:0 0 auto}
  .grp{display:flex;align-items:center;gap:8px}
  .grp-btn{display:none}
  .grp>.sub{
    display:flex;
    gap:8px;
    max-height:none;
    overflow:visible;
    margin:0;
    padding:0;
    border:0;
  }
  .mi a,.sub a{
    display:flex;
    align-items:center;
    min-height:44px;
    padding:11px 14px;
    border:1px solid rgba(23,38,35,.28);
    border-radius:var(--r);
    white-space:nowrap;
  }
  .mi:first-child a{border-left:1px solid var(--ink)}
  .callout{margin-top:10px;min-height:44px;padding:11px}
  main,.foot{margin-left:0}
  .stage{padding:0 16px 46px}
  .hero{min-height:0;padding-top:16px;padding-bottom:18px}
  .hero-band{height:11px;margin-bottom:0}
  .hero h1{margin-top:18px}
  .hero-figure{margin-top:16px}
  .stage>div.band{grid-template-columns:1fr;gap:10px}
  .foot{grid-template-columns:1fr 1fr;gap:18px;padding:30px 16px 20px}
  .foot-brand{grid-column:1/-1}
  .foot-mark{font-size:clamp(30px,9vw,54px)}
}

@media (prefers-reduced-motion: reduce){
  html{scroll-behavior:auto}
  .rv{opacity:1;transform:none}
  .rv.in{transition:none}
  .menu>li,.rail .brand,.rail .callout{animation:none}
  .grp>.sub{transition:none}
}

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