Example 2 of 2 from blog post Shifting layouts, and how to deal with them
This illustrates how ads can cause the page content to move around while you're interacting with it.
This page has ads above the header, and multiple ads within the body text.
The fix
To prevent the ads from pushing the rest of the page down, you simply add either a height or a min-height to the ad container, the value of which matches the ad's height.
Try it out
Reload the page, and watch the lower paragraphs: they no longer jump downwards as the ads appear.
First paragraph
One morning, when Gregor Samsa woke from troubled dreams, he found himself transformed in his bed into a horrible vermin. He lay on his armour-like back, and if he lifted his head a little he could see his brown belly, slightly domed and divided by arches into stiff sections. His many legs, pitifully thin compared with the size of the rest of him, waved about helplessly as he looked.
Second paragraph
His many legs, pitifully thin compared with the size of the rest of him, waved about helplessly as he looked. "What's happened to me?" he thought. It wasn't a dream. His room, a proper human room although a little too small, lay peacefully between its four familiar walls. A collection of textile samples lay spread out on the table – Samsa was a travelling salesman - and above it there hung a picture that he had recently cut out of an illustrated magazine and housed in a nice, gilded frame.
Third paragraph
It showed a lady fitted out with a fur hat and fur boa who sat upright, raising a heavy fur muff that covered the whole of her lower arm towards the viewer. Gregor then turned to look out the window at the dull weather. Drops of rain could be heard hitting the pane, which made him feel quite sad. “How about if I sleep a little bit longer and forget all this nonsense”, he thought, but that was something he was unable to do because he was used to sleeping on his right, and in his present state couldn’t get into that position.
Compare
If the ad containers don't have a defined height, they stretch vertically as the ads load. See this in action.