How to Change Header Margin to Align with Body

Site URL: https://www.matey.app/privacy-policy

Hi! I'm trying to figure out how to align my header with the body content on my site. I have the site section widths set to Medium. My template is Stanton. I'm also trying to target the header button so I can adjust the corner radius to 15px. Thanks in advance for your help!

Add to Home > Design > Custom CSS

@media screen and (min-width:641px) {
.header-announcement-bar-wrapper {
    width: 75% !important;
    margin: 0 auto;
}
}

@tuanphan Thank you I was able to align the header but I still can't figure out how to adjust the header button to have a corner radius of 15px. Do you know how to target it?