I have a layout similar to:
I would like for the div
to only exp
The answer for your question lays in the future my friend ...
namely "intrinsic" is coming with the latest CSS3 update
width: intrinsic;
unfortunately IE is behind with it so it doesn't support it yet
More about it: CSS Intrinsic & Extrinsic Sizing Module Level 3 and Can I Use?: Intrinsic & Extrinsic Sizing.
For now you have to be satisfied with or
display: inline-block;