It works fine now in Colours;
I’ll see if I can have him look at the site and offer any suggestions as to cause.
These two comments from you don’t match. The first suggests, as I expected, that the cause has been identified and a fix found. The second seems to say the opposite.
I believe I have identified the cause, and I “thought” you had confirmed it. So is there still a problem?
(Note: I’m only concerned with the colors theme that you reported. The temporary fix I provided was not designed to cater for any other theme, browser, or operating system. But it can be eventually. That is why I explicitly asked that you add the code to your mystyle.css file in the colors theme. I deliberately did not mention trying it in any other theme.)