:root{--bg:#0ea5e9;--text:#fff;--muted:#f5f5f5}*{box-sizing:border-box}body{margin:0;font-family:system-ui,Segoe UI,Roboto,Arial}.topbar{display:flex;align-items:center;padding:0 1rem;height:56px;background:var(--bg);color:var(--text)}.topbar .brand{font-weight:700}.topbar .spacer{flex:1}.topbar .btn{margin-left:.75rem}.content{display:flex;min-height:calc(100vh - 56px)}.sidenav{width:220px;background:#111;color:#bbb;display:flex;flex-direction:column;padding:1rem 0}.sidenav a{color:#bbb;text-decoration:none;padding:.75rem 1rem}.sidenav a.active,.sidenav a:hover{background:#222;color:#fff}.page{flex:1;padding:1rem}.center{display:grid;place-items:center;min-height:100vh}.card{display:flex;flex-direction:column;gap:.75rem;min-width:300px;padding:1rem;border:1px solid #ddd;border-radius:8px;background:#fff}input{padding:.6rem .75rem;border:1px solid #ccc;border-radius:6px}.btn{padding:.6rem .9rem;border:0;border-radius:6px;background:#ddd;cursor:pointer}.btn.primary{background:#0ea5e9;color:#fff}.error{color:#b00020;margin-top:.5rem}@media (max-width: 900px){.sidenav{position:sticky;top:0;width:160px}}