Sometimes a website is short, shorter than the height of your monitor. On pages like this the default is that a scroll bar is not display. However, if you then click to a page on the same website that happens to be taller than the available width on your monitor, a scroll bar will appear on the right side. This can cause the page to shift about 20 pixels to the left. It is just mildly unpleasant, but there is an easy fix. Simple apply the scroll bar to ALL pages, even the short ones. You wont notice that it is there when its not needed, and it solve the problem of the website jumping around.
In order to correct the issue, and make the page static, give all pages a scroll bar, whether they need it or not.