Hi again,
Yeah, you can debug and customize style for element in megamenu then add the style to custom.css file. Here is an example for customizing color of a sub-megamenu color.
.t3-megamenu.animate.slide .mega.open > .mega-dropdown-menu > div {
margin-top: 0%;
background: #0077bb;
}
If you want to customize style of any specific menu item, you can add class for the menu item in the Megamenu setting panel then add style for the class in the custom.css file.
Gardner.