try this
CSS
.grid_8{
width:960px;
background-color:red;
border:#FFF 1px dashed;
padding:95px 0 110px;
vertical-align:middle;
}
.grid_4{
width:480px;
background-color:blue;
border:#FFF dashed 1px;
padding:100px 0;
margin:100px 0 0 0;
}