Why does 100% not mean 100% height?

Question

I am trying to get some divss to expand to fill the screen, but I am struggling. I have broken down the issue on this jsfiddle.

What I really want to kn

Answer 1

Percentage heights in CSS don't make a lot of sense to me. I would argue that it doesn't work the way it should, but CSS enthusiasts would insist that it does.

This article discusses both the issue and solution in detail:

http://matthewjamestaylor.com/blog/equal-height-columns-cross-browser-css-no-hacks

This might help too:

 

 
    
 
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See here for more details on the above:
How to make a floated div 100% height of its parent?