How to change full-width header to box width

What I’d like to do is have the header to be boxed while having the main content staying as is.

I’ve looked at several other threads, but I couldn’t manage to make my way to the solution .

Here is my header CSS that makes its full width

.full-width-content .wrap, .full-width-content .content-sidebar-wrap {
margin: 0 auto;
max-width: 100%;
width: 100%;
}

There is not enough context for me to say anything.

Do you have a link to your demo via codepen?

I solved it out thanks for the reply btw

Just make the width : 80 %and its done