I just noticed that on sites with "auto ads" enabled, auto-placed AdSense units don't follow CSS rules regarding margin or padding in mobile view. They display across the entire viewport instead of allowing margin. The issue is not really applicable on desktop because ads rarely run border to border down to the pixel. But it does interfere with the design of mobile pages. See example below.
<head> section of your HTML, and Google's algorithms choose the sizing and placement of the ad units.
Is there a way to force margins on these units?