With this trick you can use full page background image

Full Page Background Image

<div class="s3-shaz3e">
  An Example for
</div>

style.css

html { 
  background: url(https://imageshack.com/a/img19/4153/vt2k.jpg) no-repeat center center fixed; 
  -webkit-background-size: cover;
  -moz-background-size: cover;
  -o-background-size: cover;
  background-size: cover;
  
  /* IE Fixed*/
  filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(src='.https://imageshack.com/a/img19/4153/vt2k.jpg', sizingMethod='scale');
  -ms-filter: "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='https://imageshack.com/a/img19/4153/vt2k.jpg', sizingMethod='scale')";
}
.s3-shaz3e{
  position:absolute;
  left:15%;
  top:45%;
  width: auto;
  height: auto;
  font-size:150%;
}