/* ───── Reset ───── */
*{margin:0;padding:0;box-sizing:border-box;}
img{display:block;max-width:100%;}
a{color:inherit;text-decoration:none;}
html,body{overflow-x:hidden;}
main{position:relative;z-index:2;}

/* ───── 顶部导航 ───── */
.nav{
  position:fixed;top:0;left:0;right:0;z-index:40;
  height:var(--nav-h);
  display:flex;align-items:center;justify-content:space-between;
  padding:0 var(--pad-x);
  border-bottom:1px solid rgba(126,116,105,.24);
  background:rgba(244,239,230,.88);
  backdrop-filter:blur(14px) saturate(1.1);
  transition:background .3s var(--ease),border-color .3s var(--ease),color .3s var(--ease);
}
.nav__brand{
  flex:none;
  font-family:var(--serif);
  font-size:24px;font-weight:600;letter-spacing:-.02em;
}
.nav__links{
  display:flex;align-items:center;justify-content:flex-end;
  min-width:0;
}
.nav__primary,.nav__tools{display:flex;align-items:center;}
.nav__primary{gap:clamp(16px,1.8vw,30px);}
.nav__primary a{
  position:relative;
  padding:10px 0;
  color:var(--ink);
  font:500 10px/1 var(--sans);
  letter-spacing:.1em;
  text-transform:uppercase;
  transition:color .25s var(--ease);
}
.nav__primary a::after{
  content:"";
  position:absolute;left:0;right:100%;bottom:3px;height:1px;
  background:var(--accent);
  transition:right .25s var(--ease);
}
.nav__primary a:hover,.nav__primary a:focus-visible,.nav__primary a.is-active{color:var(--accent);outline:none;}
.nav__primary a:hover::after,.nav__primary a:focus-visible::after,.nav__primary a.is-active::after{right:0;}
.nav__tools{
  gap:10px;
  margin-left:clamp(18px,2.4vw,38px);
  padding-left:clamp(18px,2.2vw,34px);
  border-left:1px solid rgba(126,116,105,.32);
}
.nav__stat{
  display:inline-flex;align-items:center;gap:7px;
  color:var(--ink);
  font:500 10px/1 var(--sans);letter-spacing:.02em;
}
.nav__stat[hidden]{display:none;}
.nav__stat i{color:var(--accent);font:400 11px/1 var(--sans);font-style:normal;}
.nav__github{
  display:inline-flex;align-items:center;justify-content:center;
  width:34px;height:34px;
  border:1px solid rgba(126,116,105,.46);border-radius:50%;
  color:var(--ink);
  transition:color .25s var(--ease),border-color .25s var(--ease),background .25s var(--ease),transform .25s var(--ease);
}
.nav__github svg{width:15px;height:15px;display:block;}
.nav__github:hover,.nav__github:focus-visible{color:var(--paper);border-color:var(--accent);background:var(--accent);transform:translateY(-1px);outline:none;}
.nav__lab{position:relative;}
.nav__lab-trigger{
  display:inline-flex;align-items:center;gap:7px;
  min-height:36px;padding:0 13px;
  border:1px solid var(--ink);border-radius:999px;
  background:var(--ink);color:var(--paper);
  font:600 9px/1 var(--sans);letter-spacing:.12em;text-transform:uppercase;cursor:pointer;
  transition:color .25s var(--ease),background .25s var(--ease),border-color .25s var(--ease),transform .25s var(--ease);
}
.nav__lab-trigger:hover,.nav__lab-trigger:focus-visible{color:var(--paper);background:var(--accent);border-color:var(--accent);transform:translateY(-1px);outline:none;}
.nav__lab-trigger .nav__lab-dot{width:5px;height:5px;border-radius:50%;background:var(--accent);}
.nav__lab-trigger:hover .nav__lab-dot,.nav__lab-trigger:focus-visible .nav__lab-dot{background:var(--paper);}
.nav__lab-trigger i{
  margin-left:2px;font:normal 14px/1 var(--mono);
  transition:transform .25s var(--ease);
}
.nav__lab-panel{
  position:absolute;top:calc(100% + 14px);right:0;
  width:min(420px,calc(100vw - 32px));padding:14px;
  color:var(--paper);background:rgba(19,17,15,.98);
  border:1px solid rgba(244,239,230,.16);box-shadow:0 28px 80px rgba(26,23,20,.28);
  opacity:0;visibility:hidden;transform:translateY(-8px);
  transition:opacity .25s var(--ease),transform .25s var(--ease),visibility .25s;
}
.nav__lab-panel::before{content:"";position:absolute;left:0;right:0;top:-15px;height:15px;}
.nav__lab:hover .nav__lab-panel,.nav__lab.is-open .nav__lab-panel{
  opacity:1;visibility:visible;transform:translateY(0);
}
.nav__lab:hover .nav__lab-trigger i,.nav__lab.is-open .nav__lab-trigger i{transform:rotate(45deg);}
.nav__lab-head{
  display:flex;align-items:center;justify-content:space-between;
  padding:5px 6px 17px;color:rgba(244,239,230,.48);
  font:400 9px var(--mono);letter-spacing:.12em;text-transform:uppercase;
}
.nav__lab-project{
  min-height:74px;padding:13px 10px;
  display:grid;grid-template-columns:28px minmax(0,1fr) auto;align-items:center;gap:12px;
  border-top:1px solid rgba(244,239,230,.14);letter-spacing:0;
  transition:background .25s var(--ease),color .25s var(--ease);
}
.nav__lab-project:hover,.nav__lab-project:focus-visible{
  color:#111;background:var(--accent);outline:none;
}
.nav__lab-index{align-self:start;padding-top:3px;color:rgba(244,239,230,.42);font:400 9px var(--mono);}
.nav__lab-project strong,.nav__lab-project small{display:block;}
.nav__lab-project strong{font:500 15px var(--sans-cjk);}
.nav__lab-project small{margin-top:5px;color:rgba(244,239,230,.44);font:400 9px var(--mono);}
.nav__lab-project i{color:var(--accent);font:normal 17px var(--mono);}
.nav__lab-project:hover small,.nav__lab-project:focus-visible small,
.nav__lab-project:hover .nav__lab-index,.nav__lab-project:focus-visible .nav__lab-index{color:rgba(17,17,17,.55);}
.nav__lab-project:hover i,.nav__lab-project:focus-visible i{color:#111;}

/* ───── 左侧韵律线(脊柱)+ 四角准星 ───── */
.rail{position:fixed;top:0;bottom:0;left:var(--rail-x);z-index:3;pointer-events:none;}
.rail i{position:absolute;top:calc(var(--nav-h) + 40px);bottom:48px;width:1px;background:var(--line);opacity:.7;}
.rail i:nth-child(1){left:0;}
.rail i:nth-child(2){left:7px;}
.rail i:nth-child(3){left:14px;}

.cross{position:fixed;z-index:3;width:18px;height:18px;pointer-events:none;opacity:.5;}
.cross::before,.cross::after{content:"";position:absolute;background:var(--line);}
.cross::before{left:8px;top:0;width:1px;height:18px;}
.cross::after{top:8px;left:0;height:1px;width:18px;}
.cross--tr{top:calc(var(--nav-h) + 22px);right:38px;}
.cross--bl{bottom:34px;left:34px;}
.cross--br{bottom:34px;right:38px;}

/* ───── CTA 按钮族 ───── */
.btn{
  display:inline-flex;align-items:center;gap:12px;
  font-family:var(--sans-cjk);font-size:16px;font-weight:400;
  transition:all .3s var(--ease);
}
.btn .arr{transition:transform .3s var(--ease);}
.btn:hover .arr{transform:translateX(5px);}
.btn--ghost{
  padding:18px 42px;border:1px solid var(--ink);
  background:transparent;color:var(--ink);
}
.btn--ghost:hover,
.btn--ghost:active{background:var(--accent);border-color:var(--accent);color:var(--paper);}
.btn--ghost:hover .arr,
.btn--ghost:active .arr{color:var(--paper);}
.btn--link{
  padding:18px 42px;border:1px solid var(--ink);
  background:transparent;color:var(--ink);
}
.btn--link:hover,
.btn--link:active{color:var(--accent);border-color:var(--accent);}

/* ───── 区块占位(临时)───── */
.section--placeholder{
  min-height:100vh;display:flex;align-items:center;justify-content:center;
  border-top:1px solid var(--line);
  font-family:var(--serif);font-size:40px;color:var(--line);
}

/* ───── reduced motion ───── */
@media (prefers-reduced-motion:reduce){
  *{animation:none !important;transition:none !important;}
}

@media (max-width:760px){
  :root{
    --pad-x:20px;
    --rail-x:20px;
  }

  .rail,
  .cross{display:none;}

  .nav{padding:0 var(--pad-x);}
  .nav__primary,.nav__stat{display:none;}
  .nav__tools{margin-left:0;padding-left:0;border-left:0;}
  .nav__lab-panel{position:fixed;top:calc(var(--nav-h) - 1px);right:12px;width:calc(100vw - 24px);}

  .btn{white-space:nowrap;}
  .btn .arr{flex:none;}
}

@media (max-width:420px){
  .nav__github{display:none;}
}