Currently, I am unable to replicate this issue, but I have encountered something similar in the past. Typically, this occurs when the element with the background does not span the entire height.
Make sure that you are applying the background to the body
element (which defaults to 100% height) and avoid adding styles to the html
tag as it can affect how the body is displayed.
If you encounter the white space again, try inspecting it for clues on what might be causing the problem.
Another potential cause could be that the GA code at the bottom of the page has not finished loading. If scripts near the end of your page take too long to execute, you may see this issue before the closing html
tag is processed.
You may find more information on a related topic in Chromium issue 5388: Chromium issue 5388