Step 1:

Create your menu(s) and menu items. If you need help doing this, refer to this previous tutorial in which we created a Control Panel menu.

Step 2:

Go to Extensions -> Module Manager. Edit the menu for which you'd like to change the style.

Step 3:

Enter these parameters:

Show Title: No
Enabled: Yes
Position: mobile-4 (if TapTheme iPhone isn't your default template you MUST type this directly into the select box)

Advanced Options -> Module Class Suffix: -list, -light, or -dark

Here's what each will look like:

-list

-light

-dark