@media(max-width:900px){.app-shell{grid-template-columns:1fr}.sidebar{position:sticky;top:0;z-index:5;border-right:0;border-bottom:1px solid var(--border);padding:14px}.brand{margin-bottom:12px}nav{display:flex;overflow:auto}.nav-item{white-space:nowrap}.grid{grid-template-columns:repeat(2,1fr)}.topbar,.content{padding:20px}}@media(max-width:560px){.grid{grid-template-columns:1fr}.topbar{align-items:flex-start;gap:12px;flex-direction:column}.content{padding:16px}}