body {
  background-image: url(image.jpg);
  background-position: center center;
  background-repeat: no-repeat;
  background-attachment: fixed;
  background-size: contain;
   -webkit-background-size: contain;
  -moz-background-size: contain;
  -o-background-size: contain;
  background-color:#fff;
  position: relative;
}

.build{
	text-align: center;
	margin: auto;
	font-size: 30px;
    font-family: sans-serif;
}

@media only screen and (max-width: 767px) {
  body {
    background-image: url(image-mobile.jpg);
  }
}