Megamenu keeps disappearing

[Goz]

Just putting together a pretty standard SD2018 site and I get a problem where the megamenu disappears from time to time.

If it is there and I refresh the page a few times then it will eventually disappear.

Similarly, if it is not there and I refresh the page a few times it will eventually reappear.

It happens on all pages I've tested.

It only seems to happen in FireFox (I've tried Chrome and Edge) so I thought it was a cacheing issue so I've cleared my FF cache.... but it still happens.

Can someone try it out in FireFox for me to prove it is a local issue for me (and put me out of my misery)?

https://cdrpumpsshop.co.uk/index.html

[NormanRouxel]

I see it failing (about 1 out of 10 times) here using Firefox. If it's missing and you resize the window it reappears but is much too tall.

Possibly because someone has relocated the load of actinic.css to the bottom of the HTML.

[Goz]

That is the issue! That was done in SD2016 to speed up page load times and works perfectly well there.... but not, it seems, in SD2018. Thank you so much for spotting that Norman.