body {
  background: #000;
}

/*
canvas {
    border: black 1px solid;
     background: #FFF; // here for the sake of demonstration only 
}
*/

body {
  align-items: center;
  display: flex;
  height: 100vh; /* Fallback for browsers that do not support Custom Properties */
  justify-content: center;
}

body, html {
  margin: 0;
  overflow: hidden;
  padding: 0;
}

canvas { 
  max-width: 100%;
  max-height: 100%;
  display: inline-block; /* Instead of display: block; */
  margin: 0 auto;
  vertical-align: middle;
  touch-action: none;
}

div {
    display:none;
}

.hidden {
    display:none;
}