How to size sub-menu

[lasa]

What I am trying to build is a mobile dropdown navigation:
MENU 320 px wide and submenus 320px as well.

MENU

Then when you click the menu the submenus appear below it (not indented) with all the page options...
all 320 px wide.

MENU
Products
Services
Contact us

I can not seem to be able to set the submenu size or add space to elongate it..
Cheers,
Lasa

[lasa]

Sorry I just saw the response a couple of threads below were it can't be done...