transparent header and slider on mobile displays

Hi,

I would like to know how I could use the navigation bar in mobile view as a transparent overlay. It now seems as if the header is above the slider, which ensures that the slider is too low. It is my intention to start the slider at the top of the page and that the menu is transparent over it. I would like to hear from you again.

And it seems that at the moment of scrolling on a mobile view, the slider is suddenly zoomed in. Can this be turned off in one way or another? And scroll in the same way as the desktop version?

Sincerely,
Martijn