It seems like that’s a lot more difficult than just using the <center> command, which, as I say, works in every other theme I’ve tried. It even works in Weaver II for the preview and then after I reinsert it after some idiotic thing removes it.
Does Weaver II remove commands that aren’t supported in HTML5 after you’ve viewed them in the preview but before they go live? That seems deceptive to me.
I’ll try using WordPress’ “built-in CSS for centering graphics,” but if it is not easy I’ll probably just find a new theme to use instead of Weaver II.