Hi Steve,
Thanks for writing in!
To remove that line, add following CSS under Custom > CSS in the Customizer:
.x-navbar .desktop .x-nav > li > a:hover, .x-navbar .desktop .x-nav > .x-active > a, .x-navbar .desktop .x-nav > .current-menu-item > a {
box-shadow: none;
}
Hope this helps. 🙂
Thank you!