how to limit the drop down width in dawn theme on my header

[pbjfg]

Hello everyone,

I'm trying to modify the width of my drop down menu so it doesn't take the whole page like in the following exemple.

So far, it takes the whole page and i don't really like it.

I would like to be align too with the title of the drop down and not  always on the left. (see picture below)

I'm currently using dawn theme V15.1 and tried to modify through the customize menu but without success so far.

Let me know if you have any solutions for these 2 problems.

Many thanks.

[pbjfg]

Found it !