.wp-block-navigation-submenu li{display:block;width:100%;border-bottom:1px solid #ccc}
.wp-block-navigation-submenu li:last-child{border-bottom:none}
.wp-block-navigation-submenu li a{display:block;width:100%;padding:16px 15px;margin:0;box-sizing:border-box}
@media (max-width: 768px) {
.wp-block-navigation-submenu li a{padding:25px}
}