[Strzelecki]

You need to do something like:

html, body {
  height:100%;
}
/*  Add this to #wrapper */
#wrapper {
  height:100%;
  min-height:100%;
}
/* fix for IE */
html>body #wrapper {
  height:auto;
  min-height:auto
}
*/ then modify the footer*/
#footer {
  position:absolute;
  width:100%;
  bottom:0;
}

This will get the footer to 'stick' to the bottom of the viewpoint or browser window depending on the page content.
You can't 'find' what you're looking for as the whitespace isn't caused by an element, it just where the bottom of the document (body) ends. It the common 100% height problem.