.divtop {
    position: fixed;
    top: 0px;
    left: 0px;
    right: 0px;
    bottom: 0px;
}

.divbody
{
    position: fixed;
    top: 140px;
    left: 0px;
    right: 0px;
    bottom: 0px;
}

.divbottom
{
    position: fixed;
    top: 600px;
    left: 0px;
    right: 0px;
    bottom: 0px;
}