[css3-values] Proposal for auto fitting value for height and width

Hello,

I'd like to propose an auto fitting value that could be used with the 
height and width propertys.

What this would do is it would have an object in the DOM fill all 
remaining space. If it is used with a child of the body element, it 
would fill the remaining screen space.

Possibly something like:

Height: fit; or width: fit; ?

Example, if an element directly opened after the body tag has an ID of 
#wrap and the stylesheet says wrap should have height: fit; then #wrap 
would fill the screen. If after #wrap is closed, and another element is 
opened with a height of lets say 100px, this element is pushed to the 
bottom, and the first element (located at the top) is given a height of 
browser window minus 100px.

Example 2, if an element has a height of 500px, and a child element has 
a height of 150px, and a sibling of that child has a height of fit, that 
element's height is 350px.

Thoughts?