Hi bubbleboy,
Because the menu item is longer than the width, you can select the larger screen(LG) in the option or change the with of the menu item with the following CSS:
@media (max-width: 767px) {
.t4-megamenu .navbar-nav>li>a, .t4-megamenu .navbar-nav>li>.nav-link {
padding: 0 1rem;
font-size: 18px;
}
}