Video theme issues in certain browsers/Safari on iPhone

Hi

Just testing the video theme (www.thevapers.org) in browsers.

OK in Chrome and FF, but not in Opera or MS Edge. Also totally screwed up in Safari iPhone browser. Looks like the .css file is missing…. I had minimized .js and .css when using Autoptimize and then installed plugins WP Fastest Cache and WP Super Cache to see which one would make significant speed improvements.

Despite deactivating all cache plugins there’s no effect – the browsers are loading the home page same as the attached image.

What am I missing? Do I need to delete the cache plugins?

Any advice? site: http://www.thevapers.org

Thanks in advance.

Cheers

Mike