@tasken
One thing that I wrote in my first intervention in this topic.
“That’s how it is by default in mobile since the header is sticky, it has some background.”
“If don’t have a solid background you will face this kind of problems when scrolling down.”
That’s how we designed it by default, since in mobile there are several restrictions due to the size limitations or mobile devices functionalities so for us there is nothing wrong to correct or we obviously already had corrected it.
The css Mohammad provided was just to help the other customer to achieve their desired look, that doesn’t mean that we will include it in the theme version.
Do you need any help in your specific situation? Then provide us further info about the issue and about your site.
-Rui