When a page on your site does not include much content, sometimes you may find that the footer "floats" in the middle of the page with space under it, as shown here:
This issue is caused when there is not enough content on the page to fill the vertical space available in the browser window.
At this time, while it is not possible to always align the footer with the bottom of the page, there are several workarounds for this issue.
Change your footer background color
A simple and fast way to resolve this issue is to change your footer background color to the same as your page background (this is typically white). While this won't move the footer down, it does make the issue less obvious from a visual standpoint.
Adding 'filler' content
Edit the page so that content takes up more vertical space. In general, you'll want to make your page content be at least 800-1,400 pixels high in total.
Additional content can include an image or more text.
Note that this content can be "filler" in the sense that it may not be crucial to the content of the page. For example, a good option is a large, generic image.