> Though some pages are too wide for portrait orientation, and not zoomable.

That’s exactly what I meant when I said half the page was lopped off.

(thinks of human Kryten in that episode of Red Dwarf trying to find the zoom function...)

Perhaps rotate your phone?

It is irritating when pages block zoom (sometimes intentionally but usually as a side effect of working around sizing oddities in some devices/browsers/versions) but here you may have all you need to solve the problem.

Unless you have a smaller device and it is still too wide in landscape orientation.

Rotating might work but the bigger problem is that it’s not immediately obvious that you’re losing half page. The retro effect makes it look like the screen fill is intentional. It’s not until you view the page on a desktop that it becomes clear just how much content is missing in portrait on mobile devices.

I got flickering when looking at it on my iPad. I’m not sure if that was a deliberate attempt to emulate a CRT (and I don’t remember any of the CRTs I had when I was a kid flickering that bad, although I have certainly used some terrible CRT screens that flickered a lot).

Certain parts of the past are not worth emulating :)

Typical CRT flicker was pretty subtle, especially at high refresh rates. It becomes more pronounced at low refresh rates, or simply bad monitors.

Making a silly effect on a website to evoke a nostalgic feeling doesn't really have to be accurate, and it'd probably be near-impossible to accurately represent the subtleties of a CRT display without compounding them with the subtleties of LCDs, especially so when the LCDs an end user will be using is an unknown.

Works fine in Firefox Focus too.