XF 1.5 Force Footer Bottom of Page


Hello! I've been having problems with my footer not being at the very bottom of my page, it seems to just float on shorter pages. Is there a way to fix this? Here's an example:

I found a post (where I got this image) that detailed how to do it but I'm relatively new to Xenforo and HTML in general, could I have a bit of help on this? Thank you in advance!