Notice that with the default printing settings, backgrounds are removed. If a user prints a page with these radio buttons, they won't be able to know which one was checked. (Inset) Box-shadows are not removed at printing, and they will a similar effect to the radial background.
Good tip, it's easy to forget about the scenario of a page being printed!
Updated with an alternate option that swaps to use of box-shadow - thanks again!
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