html, body {
    margin: 0;
    padding: 0;
    height: 100%;
    background: #000;
    overflow: hidden;
  }
  
  .rainbow {
    position: absolute;
    top: 50%;
    left: 0;
    width: 100%;
    height: 84px;
    margin-top: -42px;
    display: flex;
    flex-direction: column;
    z-index: 0;
  }
  
  .stripe { height: 12px; width: 100%; }
  .c1 { background: #7646FF; }
  .c2 { background: #285FCA; }
  .c3 { background: #07D4FF; }
  .c4 { background: #00B872; }
  .c5 { background: #FFA900; }
  .c6 { background: #FF5C00; }
  .c7 { background: #FF0000; }
  
  canvas {
    position: relative;
    z-index: 1;
    display: block;
    margin: 0 auto;
  }