html {
  height: 100%;
}

body {
  background-color: #fff;
  margin: 0;
  padding: 0;
  height: 100%;
  display: -webkit-box;  /* OLD - iOS 6-, Safari 3.1-6, BB7 */
  display: -ms-flexbox;  /* TWEENER - IE 10 */
  display: -webkit-flex; /* NEW - Safari 6.1+. iOS 7.1+, BB10 */
  display: flex;
  justify-content: center;
  align-items: center;
}

canvas {
  padding: 0;
  margin: auto;
  display: block;
}