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

.bg {
background-image: url("/image/psychopractor.jpg");
height: 100%; 
background-position: center center;
background-repeat: no-repeat;
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
}