html,body{height:100%;width:100%;margin:0;padding:0;font-family:sans-serif}#app{height:100vh;width:100vw;position:relative}#background{position:fixed;top:0;left:0;width:100%;height:100%;z-index:0;background-color:#000}.center{display:flex;justify-content:center;align-items:center;height:100%;width:100%;position:relative;z-index:1}button{padding:1rem 2rem;font-size:1.2rem;border:none;border-radius:8px;cursor:pointer;color:#fff;background-color:#007bff;z-index:2}