Make "buttons" the same size in Navigation

I've never built a site before and could really use the help!

Instead of enabling Squarespace's single button option in the Navigation Bar, I've opted to create my own multi-button list by adding in navigation links. However, I had to line-wrap one "button" and I'd like to make the backgrounds all the same size rather than have one larger than the other 2.

Website address is: www.doctorscreenvictoria.com

TIA

@Eyra123 I just checked, you can use the min-width for this situation. here is a code you need to add into CSS code.
.header-nav-list {
  .header-nav-item {
    margin-bottom: 10px !important;
    a {
      min-width: 220px !important;
    }
  }
}

see screenshot.