Customizing search bar widget in CSS

I need to make the search bar a little bit shorter in width so i can have all of my menu options fit. You can see what I mean on my site…

http://www.missionaryhealth.net

I’m not really sure what I need to do to achieve this.

Or if someone knows how i can fit all of those menu options a little tighter, I would be open to do that as well.

Thanks!