.os-header{position:fixed;top:0;left:calc(var(--taskbar-w) + 6px);right:0;height:var(--header-h);z-index:260;display:grid;grid-template-columns:minmax(220px,1fr) minmax(220px,420px) minmax(220px,.9fr);align-items:center;gap:14px;padding:10px 16px;border-bottom:2px solid var(--line);background:var(--glass);backdrop-filter:blur(18px)}
.os-header::after{content:"";position:absolute;left:0;right:0;bottom:-2px;height:2px;background:linear-gradient(90deg,var(--blue),var(--gold),var(--violet),var(--green));opacity:.24}
.os-header::before{content:"";position:absolute;inset:0;background:linear-gradient(90deg,rgba(255,255,255,.2),transparent 20%,transparent 80%,rgba(224,169,53,.02));pointer-events:none}
[data-theme="dark"] .os-header{background:var(--glass);border-bottom-color:rgba(232,228,220,.12)}
[data-theme="dark"] .os-header::before{background:linear-gradient(90deg,rgba(255,255,255,.02),transparent 20%,transparent 80%,rgba(224,169,53,.02))}
[data-theme="dark"] .os-header::after{opacity:.4}
.header-left{display:flex;align-items:center;gap:10px;min-width:0}
.brand-lockup{display:flex;align-items:center;gap:12px;min-width:0;padding-right:4px}
.brand-mark{width:34px;height:34px;display:grid;place-items:center;border:2px solid var(--line);background:var(--bg-2);box-shadow:none;flex:0 0 auto;position:relative}
.brand-mark img{width:20px;height:20px;object-fit:contain;display:block}
.brand-mark::before{content:"";position:absolute;right:-6px;top:5px;width:6px;height:12px;background:var(--gold);border-top:2px solid var(--line);border-bottom:2px solid var(--line)}
.brand-title{font-size:10px;font-weight:700;letter-spacing:.24em;text-transform:uppercase;color:var(--text)}
.brand-sub{margin-top:3px;font-size:7px;letter-spacing:.18em;text-transform:uppercase;color:var(--muted)}
.breadcrumb{min-width:0;display:flex;align-items:center;gap:8px;border-left:1px solid var(--line-2);padding-left:12px;color:var(--muted);font-size:8px;letter-spacing:.18em;text-transform:uppercase;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.section-toggle{width:34px;height:34px;border:1px solid var(--line-2);background:transparent;display:none;place-items:center;flex:0 0 auto;color:var(--muted)}
.section-toggle:hover{border-color:var(--line-3);background:rgba(224,169,53,.04);color:var(--gold)}
.header-search{height:34px;display:flex;align-items:center;gap:8px;border:1px solid var(--line-2);background:var(--bg-2);padding:0 10px;min-width:0;transition:border-color .18s,background .18s,box-shadow .18s}
.header-search:focus-within{border-color:var(--line-3);background:#fff}
.header-search svg{width:12px;height:12px;color:var(--muted);flex:0 0 auto}
.header-search input{min-width:0;width:100%;border:0;outline:0;background:transparent;color:var(--text);font-size:11px}
.header-search input::placeholder{color:var(--muted-2)}
.key-hint{font:700 8px var(--mono);letter-spacing:.02em;color:var(--muted);border:1px solid var(--line-2);padding:2px 5px;background:var(--bg);min-width:22px;text-align:center;opacity:.9}
.header-actions{display:flex;align-items:center;justify-content:flex-end;gap:6px;min-width:0}
.h-action{position:relative;width:32px;height:32px;display:grid;place-items:center;border:1px solid var(--line-2);background:transparent;color:var(--muted);transition:transform .18s,border-color .18s,background .18s,color .18s,box-shadow .18s}
.h-action:hover{transform:translateY(-1px);border-color:var(--line-3);background:rgba(224,169,53,.04);color:var(--gold)}
.h-action svg{width:14px;height:14px;stroke-width:1.55}
.h-action .badge{position:absolute;top:-6px;right:-6px}
.clock-chip{height:32px;display:flex;flex-direction:column;align-items:flex-end;justify-content:center;padding-left:10px;border-left:1px solid var(--line-2);font-family:var(--mono);white-space:nowrap}
.clock-chip strong{font-size:10px;letter-spacing:.12em;color:var(--text);font-weight:600}
.clock-chip span{font-size:7px;letter-spacing:.14em;text-transform:uppercase;color:var(--muted)}
.back-button{width:30px;height:30px;border:1px solid var(--line-2);background:transparent;display:grid;place-items:center;color:var(--muted);font-size:20px;line-height:1;flex:0 0 auto}
.back-button:hover{border-color:var(--line-3);background:rgba(224,169,53,.04);color:var(--gold)}
@media (max-width:980px){.back-button{width:34px;height:34px;font-size:22px}.header-left{gap:8px}}