.main-nav{display:flex;gap:8px;padding:12px 18px;background:#fff;border-bottom:1px solid var(--line);position:sticky;top:0;z-index:10;overflow-x:auto}
.main-nav button{white-space:nowrap}
.main-nav button[aria-current="true"]{background:var(--brand);color:#fff}
.product-shell{display:grid;grid-template-columns:minmax(0,1fr) 290px;gap:18px;padding:18px;max-width:1500px;margin:auto}
.topic-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(210px,1fr));gap:10px}
.topic-card{border:1px solid var(--line);border-radius:12px;padding:12px;display:grid;gap:6px}
.topic-card span{color:var(--muted);font-size:.9rem}
.program-total{font-size:1.1rem;font-weight:800}
.library-tabs{display:flex;gap:8px;list-style:none;padding:0;overflow-x:auto}
.empty-state{color:var(--muted)}
@media(max-width:900px){.product-shell{grid-template-columns:1fr;padding:10px}.product-shell aside{display:none}.topic-grid{grid-template-columns:1fr}.main-nav{padding:8px}}