Question About Mobile Ads

Hello!

I have a question about mobile ads. I see that I can set the ad size, but I’m not seeing an option to set a different ad size for mobile. I see that I can set the ad to only display on desktop or mobile, but then I would have to create two seperate ads for every ad – e.g. one for desktop and one for mobile. Is there custom CSS I can add to automatcially scale the ad size down on mobile? I do have the “Check this option if the size of image ads is not adjusted responsively by your theme.” checkbox selected, but our ads on mobile are still larger than we would like.

Thanks for your help!