*{box-sizing:border-box}body{margin:0;font-family:system-ui,-apple-system,Segoe UI,sans-serif;background:#0f172a;color:#e2e8f0}button{background:#334155;color:#e2e8f0;border:1px solid #475569;border-radius:6px;padding:6px 12px;cursor:pointer}button:hover{background:#475569}button:disabled{opacity:.5;cursor:not-allowed}input{background:#1e293b;color:#e2e8f0;border:1px solid #334155;border-radius:6px;padding:6px 10px}.app{display:flex;height:100vh}.sidebar{width:260px;border-right:1px solid #334155;overflow-y:auto;padding:12px}.main{flex:1;display:flex;flex-direction:column}.messages{flex:1;overflow-y:auto;padding:12px}.composer{border-top:1px solid #334155;padding:12px;display:flex;gap:8px}.user{padding:8px;border-radius:6px;cursor:pointer}.user:hover,.user.active{background:#1e293b}.msg{padding:6px 0}.msg .who{font-size:12px;color:#94a3b8}.msg .body{padding:4px 8px;background:#1e293b;border-radius:6px;display:inline-block}.auth{max-width:360px;margin:80px auto;display:flex;flex-direction:column;gap:12px;padding:24px;background:#1e293b;border-radius:8px}.auth input{width:100%}.auth button{width:100%;padding:8px}.error{color:#f87171;font-size:13px}h1{font-size:18px;margin:0 0 12px}h2{font-size:16px;margin:0 0 8px}