body.oe_single_form{
 background: url(../img/bg_skp.jpg) no-repeat center center fixed; 
  -webkit-background-size: cover;
  -moz-background-size: cover;
  -o-background-size: cover;
  background-size: cover;
}

div.oe_single_form_container {
background-color:rgba(255, 255, 255, 0.3);
}