I like fluid themes, all my themes are fluid, the other day playing with the min-width, max-width, and just width, I found out something interesting.
My theme has 3 columns, 1 content in left column, and 2 sides bars in right column. If I set both of these width with max-width, the content will shrink to the size of the content page (narrower width).
If I set my both columns to min-width, the side-bars pushed all the way down, off the page.
If I set both with just width – everything will fit in place as designed.
If I set min-width to content column and width to sidebars (right column), the page also display correctly without content shrinking.
So, next time when you change your theme CSS, if you run into displaying problem, these min-max may be the cause of it.