*{margin:0;padding:0;box-sizing:border-box}body{font-family:Segoe UI,Tahoma,Geneva,Verdana,sans-serif;background-color:#f5f5f5;color:#333}.app-container{max-width:1600px;margin:0 auto;padding:20px}button{cursor:pointer;padding:8px 16px;background-color:#0078ff;color:#fff;border:none;border-radius:4px;font-weight:500;&:hover{background-color:#0056b3}&:disabled{background-color:#ccc;cursor:not-allowed}}.error{color:#d32f2f;font-size:12px;margin-top:4px}