Removing a border at the very bottom of Handy theme header is problematic for some of our clients and needs certain clarification.
Removing it is quite simple. You need to add the following CSS code to Appearance -> Customize -> Additional CSS:
/* Remove border bottom of the header */
.header-primary-nav {
box-shadow: none;
-webkit-box-shadow: none;
}
Save changes and refresh your home page, the border should be gone.