If you want to add specific styles to menu items in WordPress You don’t have to go through all the php code, you can just simply add classes every menu items or a group of menu items with single class, then you can add styles from WordPress theme editor.
- Login into the WordPress Dashboard.
- Goto Appearance -> Menus,
- Click on Screen Options from the top right of the screen.
- Screen Options window displayed, under the Show Advanced Menu properties select the Class Properties Check box.
- Now click on the triangle next to each menu item, CSS Classes text box appears, add the css classes to menu.
- After that you can add the styles from WordPress Theme editor (Appearance -> Editor)