* { margin:0; padding:0; box-sizing:border-box; }
body { position:relative; background:#000; display:flex; justify-content:center; align-items:center; min-height:100vh; overflow:hidden; }
canvas { display:block; position:relative; z-index:2; }
#v { display:none; position:absolute; top:50%; left:50%; transform:translate(-50%, -50%); z-index:1; }