:root{--surface:#f4f5f7;--surface-elevated:#fff;--line:#dfe3eb;--text:#1f2937;--muted:#6b7280;--primary:#2563eb}*{box-sizing:border-box}body{color:var(--text);background:var(--surface);margin:0;font-family:Inter,system-ui,-apple-system,Segoe UI,Roboto,sans-serif}.app-shell{flex-direction:column;min-height:100vh;display:flex}.app-header{border-bottom:1px solid var(--line);background:#fff;padding:1rem 1.5rem}.app-brand{margin:0;font-size:1rem;font-weight:700}.app-subtitle{color:var(--muted);margin:.25rem 0 0;font-size:.9rem}.app-content{flex:1;grid-template-columns:260px 1fr;gap:1rem;padding:1rem;display:grid}.app-sidebar{border-right:1px solid var(--line);padding-right:.75rem}.app-nav{flex-direction:column;gap:.5rem;display:flex}.app-nav-item{color:var(--text);border:1px solid var(--line);background:var(--surface-elevated);border-radius:.5rem;padding:.65rem .8rem;text-decoration:none;transition:all .15s}.app-nav-item:hover,.app-nav-item:focus-visible,.app-nav-item.is-active{border-color:var(--primary);color:var(--primary);outline:none}.app-main{background:var(--surface-elevated);border:1px solid var(--line);border-radius:.75rem;padding:1rem}.page-title{margin:0 0 .25rem}.page-description{color:var(--muted);margin:0}.page-card{border:1px dashed var(--line);background:var(--surface);border-radius:.5rem;min-height:170px;margin-top:1rem;padding:1rem}.empty-surface h2{margin-top:0}.empty-surface a{color:var(--primary)}@media (width<=900px){.app-content{grid-template-columns:1fr}.app-sidebar{border-right:0;border-bottom:1px solid var(--line);padding-bottom:.75rem}}