Remove gradient colour

hello,

First question:
is it possible to remove the gradient colour from my home page:
https://luckrnt213.213.axc.nl/

Second question:
Is it possible to let the menu out when u clicked on it.
So when it slides out –> it stays out the whole visit on the website.

third question:
The navbar-brand is the same as the logo in the menu slide.
Can i have a different logo in the menu slider?

fourth question:
I’ve tried many things. how can i remove the background colour of the navbar-brand?

Sorry for so many questions in one topic but i dont want to spam the forum.