Sticky Navigation- Miller template

Site URL: https://kimusubimassage.com/

Hi everyone!

Currently, the top part of every page on my website has a navigation menu of six buttons plus the "home" button. I can't figure out a way to make this menu sticky, so that when a visitor scrolls down, the buttons follow along the top. Note that this is for the desktop site. I was able to select an option for this for the mobile version. My workaround has been to add linked buttons for each of the other pages at the bottom of each page, but I would like to get rid of those. I would really appreciate an assist!

Add to Home > Design > Custom CSS

header.Header.Header--bottom.Header--overlay {
    position: sticky;
}