SP 2010 main area padding cut off

I have custom CSS for my SP collaboration site so that it has a fixed width and it's centered.

This code does that:

#s4-bodyContainer {
width: 950px !important;
height: 100% !important;
min-height:100% !important;
margin-left:auto;
margin-right:auto; }

I have a grey background so I added this code to give the main area a bit of padding (so the content isn't flush against the edge of the main area)

#s4-mainarea {
background-color: white;
padding-left: 15px;
padding-right: 15px;
width: 920px !important; 
height: 100%; }

It works great, but the height doesn't go 100%. It works for roughly 1000 pixels and then it seems like the main area just cuts off. How do I force the main area and it's padding to keep going?

Screens: