How to set Menu bar widht 100%

Hi is it possible to set the menu bar width so that extends to 100% of the visible area of the template?

i mean the orizontal menu

i didi this by designing the template but it takes some extra work that i would like to avoid for every site i admin

you can see the result i want to get there

www.formazioneyoga.it

Hi
as you said it is a design from the template, you can't ask to style the whole menu without taking care of the template. This is special and needs to be done in the template itself.
Ced