html, body {
    height: 100%;
    margin: 0px;
    padding: 0px;
    overflow: hidden;
}

#checkout {
  height: 80%;
  width: 80%;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  position: fixed;
  overflow: auto;
}

canvas {
  width: 100vw;
  height: 100vh;
  display: block;
  position: fixed;
  top: 0;
  z-index: 1;
}