Please open templates/ja_appolio/css/custom.css file (if this file doesn’t exist, just create one in the same folder) and add the following CSS rule:
.t3-megamenu .open > .mega-dropdown-menu > .mega-dropdown-inner > .row > .mega-col-nav {
border-left: 1px solid #ddd;
padding: 20px;
}
.t3-megamenu .open > .mega-dropdown-menu > .mega-dropdown-inner > .row > .mega-col-nav:first-child {
border-left: 0;
}
.t3-megamenu .mega-nav > li a, .t3-megamenu .dropdown-menu .mega-nav > li a, .t3-megamenu .dropdown-menu .mega-nav > li .separator {
padding-left: 0;
}
That should help to add a vertical divider you mentioned.