Submenue (+) disapeare sometimes

This tool is what I've looking for. Sadly in cellphone-size the text in the submenues disapeares completly (black frame). If I restart my browser it works. But after some navigation the text of the sub menues disapeare again. See screen shot. This happens in Brave (1.63). In Chromium (96.0) and Firefox (68.9) it does not work at all.
Does some one has any idea if this is related to some settings?
Thanks in advance. Peter Pan

Hi
do you have a cache enabled on your website ? this could explain this strange behavior
please give me the url of the page so that I can check by my side
CEd

Dear CEd,
    thank you very much for the quick reply!
    I've checked the cache in Joomla (3.10) and it is deactivated. The browser I usually use is Brave (1.63....) and even on reload without using cache (shift + reload icon) it shows the same behaviour. If I restart the browser all works fine until I surf a little bit around. 

    Here my page - it's commercial and I would be happy to pay for a working "cellphone" appearance:
    German version... and the same problem in the english version with - of course - a different css-tag for the 2nd and 3rd menue.
     borgmann-aquaponik-hydroponik.ch/po9d/index.php/de/
    English version...
     borgmann-aquaponik-hydroponik.ch/po9d/index.php/en/

Kind regards, Helmer

PS:
It works:  borgmann-aquaponik-hydroponik.ch/_tempo/work-1-details.jpg
And not:  borgmann-aquaponik-hydroponik.ch/_tempo/work-1-not-details.jpg
From somewhere the "hidden" is now part of it:  borgmann-aquaponik-hydroponik.ch/_tempo/...t-details-hidden.jpg
​​​​​​​
 

ok I have seen the problem, there is a css conflict
I don't know why but the submenu gets the class "hidden"
to avoid this problem, you can add this custom css to your page

Dear CEd,
it works perfect. Even on Firefox, Chromium and Android/Brave.
I have just purchased a license. I think that's the least I can do as a thank you.
Thank you very much - this solves one of the biggest problems I've had with 
mobile device capability.
Cheers, Helmer
 

great
thank you for your purchase