.header{
  position:fixed;inset:0 0 auto;z-index:100;height:var(--nav-h,64px);
  background:var(--surface,#fff);border-bottom:1px solid var(--line,#e5e5e5);
  display:flex;align-items:center;justify-content:space-between;
  padding:0 clamp(20px,5vw,48px);
}
.header img{height:48px;width:auto;display:block}
.header a.logo{text-decoration:none;position:relative;z-index:102}
.nav-toggle{
  display:none;flex-direction:column;justify-content:center;gap:5px;
  width:44px;height:44px;padding:10px;
  border:1px solid var(--line,#e5e5e5);border-radius:8px;
  background:var(--surface,#fff);cursor:pointer;position:relative;z-index:102;
}
.nav-toggle span{
  display:block;height:2px;width:100%;background:var(--text,#1a1a1a);
  border-radius:1px;transition:transform .2s,opacity .2s;
}
.nav-toggle[aria-expanded="true"] span:nth-child(1){transform:translateY(7px) rotate(45deg)}
.nav-toggle[aria-expanded="true"] span:nth-child(2){opacity:0}
.nav-toggle[aria-expanded="true"] span:nth-child(3){transform:translateY(-7px) rotate(-45deg)}
.nav{display:flex;gap:24px;font-size:14px;font-weight:500;align-items:center}
.nav a{color:var(--muted,#5c5c5c);text-decoration:none;transition:color .2s}
.nav a:hover,.nav a.active{color:var(--text,#1a1a1a)}
.nav-backdrop{
  display:none;position:fixed;inset:0;z-index:98;
  background:rgba(0,0,0,.4);opacity:0;pointer-events:none;transition:opacity .25s;
}
.nav-backdrop.is-open{opacity:1;pointer-events:auto}
@media(max-width:768px){
  .nav-toggle{display:flex}
  .nav{
    position:fixed;top:var(--nav-h,64px);right:0;left:0;z-index:101;
    flex-direction:column;align-items:stretch;gap:0;
    background:var(--surface,#fff);border-bottom:1px solid var(--line,#e5e5e5);
    padding:12px clamp(20px,5vw,48px) 20px;
    box-shadow:0 12px 32px rgba(0,0,0,.1);
    transform:translateY(-8px);opacity:0;pointer-events:none;
    transition:transform .25s,opacity .25s;
  }
  .nav.is-open{transform:translateY(0);opacity:1;pointer-events:auto}
  .nav a{padding:14px 0;border-bottom:1px solid var(--line,#e5e5e5);font-size:15px}
  .nav a:last-child{border-bottom:none}
  .nav-backdrop{display:block}
}