To add a button to Nav bar in Five Template Squarespace, you can follow these steps
#1. First, you need to know this
#2. Suppose we need to make Sign in become a button, we will add this code to Website > Website Tools > Custom CSS.
nav#main-navigation>ul>li:nth-child(6)>a, nav#mobile-navigation>ul>li:nth-child(6)>a {
background-color: #f1f;
color: #fff !important;
padding-left: 20px;
padding-right: 20px;
border-radius: 10px;
display: inline-block;
}
#3. Result