Many AdSense publishers become desperate when their click-through rate (CTR) and cost per click (CPC) consistently remain low and as a result online income also remain low. They try everything to boost AdSense earnings. This include, changing ad types, changing ad locations and ad styles etc. AdSense provides several options to change the look and feel of your ads. But sometimes these options don't feel enough to help and grow your online income. At this juncture, AdSense publishers often start think of altering ad styles (like font-color, font style and size etc.) with the help of CSS.
The question arises, is it allowed to change AdSense ad with CSS?
No! it is not allowed by AdSense Term of Service (TOS). If you'll use CSS to change appearance of ads –you might risk losing your AdSense account.
It is an often asked question. You might have noticed that some big and well-known websites seem to use CSS to alter their AdSense ads appearance. This might give you an impression that it is possible for all the publishers.
But that is not so!
Some publishers are given the status of Premium Publishers by Google. These AdSense publishers have special privileges that regular publishers don't have. Premium Publishers are allowed to use CSS on their ads.
Your next question would most certainly be “How to become a Premium AdSense Publisher?”
Well, the status of Premium Publisher cannot be bought or applied for. Google invites certain publishers to become Premium Publishers. The criteria for such an invitation are not public; but it is safe to assume that you need to be getting millions of ad impressions and you should be strictly following AdSense Terms of Service in order to be considered by Google for Premium Publisher’s status.
There is no shortcut to AdSense success. Let me repeat, it needs hard work, time and lots of good quality content. I hope now your question is answered. You can not and should not change AdSense ad appearance using CSS. Please feel free to ask if you have any questions on this subject.