When viewing the site on my mobile phone, the subtitle and buttons in the Welcome section disappear, was that intentional? Yes I did

Did you add code to hide it on mobile devices? —> Yes I did

I set 20% 80% for every resolution, and 20% 21% for mobile.
For mobile is OK.

Can you advice any % for all the devices?
Is there any rule?

Thank you,
Nicola