CSS - Height of 100% minus #px - Header and Footer

Question

The webpage in question looks like this:

// The Header //
/*            */
/*  CONTENT   */
/*            */
// The footer //

Both the head

Answer 1

Place a fixed position on the header and the footer and set them to stick to the top of bottom of the window, respectively. Then place a top and bottom padding on the content area of 20px.

#header{position:fixed;top:0}
#footer{position:fixed;bottom:0}
#content{padding:20px 0}