*{margin:0;padding:0;box-sizing:border-box}html,body{width:100%;height:100%;overflow:hidden;background:white}#app{width:100%;height:100%;position:relative}canvas{width:100%;height:100%;display:block}#error-message{position:fixed;top:50%;left:50%;transform:translate(-50%,-50%);background:rgba(255,0,0,.8);color:#fff;padding:20px;border-radius:5px;display:none}