Navigation full width container

Hi

My general layout container width is set to 1240px. This is fine and the content should have this width.

However, I would like to make the navigation full width and without padding/margin on the left or right. So the header should be wider than the rest of the content.

If you scroll down, the sticky header already looks like I wish. So the initial header/navigation should look exactly like the sticky header when it comes to its width (no margin left and right). I tried this one:

.site-header > .inside-header .grid-container:nth-child(1) {
	max-width:5000px!important;
	padding:10px!important;
}

Has not the effect I aim for.
Any ideas?

Thank you,
Michael