That was really helpful. Thanks for taking the time to look.
In my CSS, that was the only (well, according to w3.org) error and I fixed it. But…didn’t fix problem.
Went through wp_add_inline stuff in my code — still no joy. (And I was so SURE that was problem.)
Finally, went to w3.org and ran whole page instead of individual css files.
Saw reference of error in plugin css (fortunately included name of plugin because it was sort of appended to file dynamically) and turned off just that plugin. That solved the problem, letting AutoOptimize do its thing.
The plugin included options for selecting colors within it, then emitted CSS, I guess? Anyway, solved my AutoOptimize problem.
Your tip about it being problem when logged OFF really helped me test. (Because…I was checking on phone and Ipad without logging in, but thought the format (mobile/responsive) was the problem, not being logged in/out.)
Thanks again! Whew!
Really runs faster now.