html,body{
position:relative;
background: transparent;

}
.sketch{
position: absolute;
 top: 0;

}
body{cursor:url("https://images.cnblogs.com/cnblogs_com/sunpengwei/965043/o_200527081241pen.png"),auto;z-index:1;}

#canvas{
    display: block;
    background: #ffffff;
     margin: 0 auto;
     position: fixed;
     z-index: -1;
     width: 100vw;
    height: 100vh;
    top: 0;
    left: 0;

}