I've switched the server over to PHP 7.4 (from 5.6), made what changes seemed to be necessary to silence deprecation warnings, seems to have been pretty painless, but let me know if there are any issues.
The only issue I'd like to mention is that I use the Dark Background and Light Text Firefox extension, and I think due to the recent PHP upgrade it no longer works on hcs64. Any idea why this might be? Or, would it be easy enough to add a dark theme option to the forum?
Yeah that's really weird, I didn't make any change to the stylesheets, and I tried running the old code and it still doesn't work with that extension, though it's still running on PHP 7.
Are you sure it had worked recently before this change, which I made just before I posted that message? All I can think of is the headers might have changed somehow, but given that the effect works on the old guestbook it doesn't seem like that could be it.
Hmm, if I remove the content security policy it seems to work. But that was added last year, so if you had seen this working recently that wouldn't have been the reason for a change. It's very restrictive, but I don't know how to loosen it up for a web extension like that.
[edit]
It's not great, but I've added a dark mode that activates with prefers-color-scheme: dark, hopefully that will be useful as most browsers support that now.
I'm not sure how recently the extension stopped working, but I visit this forum semi-regularly and I only noticed it a few days ago. It seemed most likely to be associated with the PHP upgrade, but I also wouldn't have any real clue as to why.
Anyway, it's water under a bridge, this solution works great for me, thank you hcs!
I noticed the exact same thing with Dark Background and Light Text and was wondering why until I randomly stumbled upon this thread.
According to the browser console, it's due to the CSP of the server:
Content Security Policy: The page’s settings blocked the loading of a resource (“style-src”).
Update: looks like hcs already mentioned the CSP. If your system uses light mode, but you want dark mode, Firefox can force the site's dark mode with this extension.
Also on Firefox, no need for an add-on if you're comfortable changing prefs in about:config, set ui.systemUsesDarkTheme to 1, that will force prefers-color-scheme to dark.