How to add a call to action button in main navigation? (Om Template)

Site URL: https://www.dearbhlaglynn.com/

Hi, I used the following code to add a call to action button in the main navigation bar. Problem is, i'm also getting the buttons on the drop down menus in the navigation. Could someone help me edit the code so it's in the main navigation bar only and not the drop-down? Thanks so much. 

.main-nav li:last-child a {
   background: #000;
   color: #fff !important;
   padding: 10px 20px !important;
   border-radius: 20px;
}

It looks like you solved with this code?

.main-nav>ul>li:last-child a {
    background: #000;
    color: #fff !important;
    padding: 10px 20px !important;
    border-radius: 20px;
}