Max-width Inset Header / Announcement bar with margins on each side

Grateful for any help towards the following...

I'm attempting to get my entire header bar to have a max-width and the dark grey margins on both sides. I was able to only somehow get the right side (see attached screenshot: indicated by the red star), but as for making the full announcement bar (screenshot: circled, left side) have the same dark grey margins, I'm currently at a loss. I do have a secondary header on here as well.
Any ideas?

fplegal.squarespace.com
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12 hours ago, Web_Solutions said:

Just add these code on Custom CSS panel.

body.tweak-subnav-position-top #wm-subnav {
    width: 100% !important;
    left: 0 !important;
}

 

Perfect! Thank you very much!!!