Fix the position of the banners

Fixes bugs with the first position in parallax banners.

https://trello.com/c/Ctzkwi65/326-parralax-headers-and-weekly-photos-often-broken-in-safari
https://trello.com/c/TfAmgTAx/341-banner-in-interests-not-displaying-correctly-again


if the ads are loaded in the onload event, then this is done right, because the viewport changes again when they show up, so its better to adjust the position of the banners after this change of the viewport.