Have you noticed yellow background on your Google AdSense unit in case Adds are a bit different format then your AdSense placeholder?
|Remove yellow background color|
This trick will help you to remove yellow Google Adsense background. Although this is not really bug or a bad thing, it could be annoying for visitors or even confusing. However, it is good to make steps necessary to make things work good. If you worry about editing your WordPress Theme I suggest you to ask for help from someone who knows CSS basics.
To make changes to your CSS simply LogIn into your WordPress site as Administrator and navigate to Appearance > Edit CSS. Then copy/paste these few lines of CSS code right after text or code you have already have in a CSS field
Click Save Stylesheet and your work is done. I have wrote this post by using original article written by John Shipp. There, on his link you can find explanation for this behavior and few more ways to deal with this problem.