html, body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
}

body {
  min-height: 100%;
  height: auto !important;
  height: 100%;
  position: relative;
}

#center {
  width: 100%; 
  text-align:center;
  position: absolute;
  top:45%;
  z-index:10;
}