That approach is going to be troublesome. The jQueryUI menu is going to be clashing with the ASP.Net menu implementation as both are going to enhance the same elements to create a menu.
Assuming there is a reason you can't completely switch to using the jQueryUI menu. With a little digging into the markup and styles generated by both menus, you could style the ASP.NET menu similarly to the jQueryUI menu. If you need to dynamically set themes (ex. different theme for different users) then I would really try to switch to the jQueryUI menu so you have a single "skin" defined.
The intricacies of styling the ASP.Net menu is a different forum. Here is something minimal to get you started.
With ASP.NET 4.0, have a menu control with a CssClass of menu. Then use the following CSS:
- .menu ul {
- border: 1px solid #aaaaaa;
- background: #ffffff;
- color: #222222;
- border-radius: 4px;
- display: list-item;
- margin: 0;
- padding: 0
- }
- .menu li {
- width: 150px;
- display: block;
- padding: 2px .4em;
- line-height: 1.5;
- min-height: 0;
- font-weight: normal;
- }
- .menu a {
- color: black;
- text-decoration: none;
- white-space: nowrap;
- display: block;
- }
- .menu a:hover, a:active, highlighted {
- cursor:hand;
- border-radius: 4px;
- border: 1px solid #aaaaaa;
- background-color: #dadada;
- font-weight: normal;
- color: #212121;
- margin: -1px;
- }
