If you want to add customized the HTML attributes such as id and class of the menu items, the Menu attributes module could help.

Download and install the module @ Drupal – Menu attributes

 

Try editing a menu item and you will find an extra pane called Menu item attributes

 

Let’s add the id, class and a inline CSS style for this menu item.

 

Save and check it out.

 

Done =)

Reference: Drupal – Menu attributes