Content Jumping (and How To Avoid It)
Few things are as annoying on the web as having the page layout unexpectedly change or shift while you’re trying to view or interact with it. Whether you’re attempting to read an article as it wriggles around in front of you, or you try to click a link only to have another one push it out of the way and take you off to somewhere unexpected, it’s always frustrating.
Source: Content Jumping (and How To Avoid It), an article by Brandon Smith.