html {
  height: 100%;
  overflow: hidden; }

body {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  -webkit-box-shadow: 0 0 200px rgba(0, 0, 0, 0.4) inset;
          box-shadow: 0 0 200px rgba(0, 0, 0, 0.4) inset;
  -webkit-box-pack: center;
      -ms-flex-pack: center;
          justify-content: center;
  -webkit-box-align: center;
      -ms-flex-align: center;
          align-items: center; }