html, body {
  height: 100%;
  min-height: 100%;
}
 
body {
  font: 15px arial;
  color: rgba(0, 0, 0, .7);
}
 
.wrapper {
  height: 100%;
  min-height: 100%;
  display: -webkit-flex;
  display: flex;
  -webkit-align-items: center;
  align-items: center;
  -webkit-justify-content: center;
  justify-content: center;
}