Hi inventive_vision,
On T3 templates, we use the .less files to store the defined css styles of the template layout. It will be quitely not simple to edit and easy to be overridden while updating the template, so that i suggest you to create a custom.css file at templates/ja_beranis/css/ path, then put below codes into:
/* Parent menu item font-size*/
.t3-mainnav .navbar .nav>li>a {
font-size: 11px;
}
/* First level child menu item font-size*/
.t3-megamenu .mega-group .mega-nav > li a,
.t3-megamenu .dropdown-menu .mega-group .mega-nav > li a {
font-size: 13px;
}
Change to your desired font-size value.
