Question: How can I set a "spacer" div to fill remaining height space between CONTENT and FOOTER, so footer will be always at the bottom of the page (not window as originally asked)? 
Here is a example where footer is not at the window's bottom: <http://template1.staceyapp.com/> (I'm using this template, so structure is the same).
I've tried many things like creating a div and setting it to be min-height, height 100% etc. 
Probably Javascript is needed for that. 
Are you able to help me setting jQuery to calculate it's height to fill the remaining space?
Is there a better solution?

Many thanks in advance,
Graxa

Answer: 
It sounds like you want a sticky footer, which sits at the bottom of the browser window or at the bottom of the content, whichever happens to be longer.

If that's true, check out: <http://ryanfait.com/sticky-footer/>
Have you tried to set the footer just to position:fixed on the bottom?