html,body,#app{height:100%}body{margin:0;user-select:none}#app{background-color:#f5f5f5;display:flex;justify-content:center;align-items:center}.controller{position:fixed;top:0;bottom:0;left:0;right:0}.controller button{width:56px;height:56px;position:absolute;opacity:.5;border:none;border-radius:50%;background-color:#f5f5f5}.controller button:hover{opacity:.8}