fiddle
Your problem is, which you dint noticed, Assuming just for heights
height:100%;
border: 5px solid red;
padding: 15px;
margin: 20px;
This makes height = 100% + border (2 x 5) + padding (2 x 15) + margin
(2 x 20) = 100% + (10+30+40) px
which is more than 100%...hence no fit block in body area..Try reducing with height in percentage for better result!!
Similar is case for the widths!!
