Fixed (sticky) Header

Hi

your theme looks fantastic, thank you very much for this free theme.

I have 2 questions, because i can`t solve the problem by myself:

(1) I like to have a complete fixed header for desktop and mobile (header with top navi, site title and sub-navi), which change background from black to white if the user scroll down the page. Is this possible?

(2) FYI: If i used the boxed layout the header is not sticky?

Thanks
Frank