Having the Menu on a Phone be expanded automatically

I was wondering if there is a way for the menu on the Phone Screen to be “Autoexpanded”

for Example.

Right now If I go to the Menu on my phone. It has that little 3 line icon to expand the menu.

Where in the css or place do I change that so instead of having to hit that little 3 line icon it just expands when they go through the menu. Or even allow me to customize the way that menu looks?

For Example…
on the phone screen… when they go to the site it would show

Item1
Item2
Item3

Rather than the 3 line icon?

Any help is appreciated!