If you are using Adsense to monetize your WordPress blog, chances are the Adsense ad units have a yellow background on them. This is because Google uses <ins> tags to wrap the code for the Adsense ads. In WordPress, the code standard for ins tags is to include Yellow background a and this can be found in multiple WordPress themes.
The yellow background has other issues like it might decrease the CTR for the ads resulting in a decrease in revenue. Fortunately, this can be resolved easily.
How to remove the yellow background from Adsense ads in WordPress
Go to Appearance –> Editor and edit style.css (or custom stylesheet if you are using) to add the following code at the end.
background-color: #FFFFFF !important;
Save the edit and the yellow background will be gone from the Adsense ads.