Hello again,
Well, it still doesn't work quite well on the phone (the slider is still cut a bit), works when I simulate the view on mobile from desktop browser (on my PC), it still doesn't work quite well when I preview on my mobile device vertically (in this case I use Galaxy Note 10+ with FHD+ resolution).
It clearly seems to be connected with break points...
Anyway I was forced to increase the value of breakpoint from standard 576 to 676 or even 776 (to make it work on mobile), and again - when I did it - it started to work perfecly when I simulated mobile view on PC, but its seems it has no efffect on mobile browser directly. I tested it with several mobile browsers with dumped cache memory of course.
Here go the link to test site. Please note: @media (min-width: 776px) (is even changed to 776 instead standard 576)
Could you please test it on your phone to check if the slider is still cut.
https://www.itarts.pl/bsduszniki-test/index-start.html
Moreover - I tried with custom heights, added a few classes like .min-vh-10 etc. but the result was weird because the slider on mobile device... disappeared, when I used standard .min-vh-25 class back the slider was visible again.
Thanks again for your help!