drop down menu child background length…css for custom nav?

hi,

i’m working on a main navigation menu that has a drop down menu item, with custom css (from the appearances->menus).
i want the font to be a larger size, which i can create via the header style area in the theme i am using…but i am having trouble adjusting the width of the background so it extends to accommodate the longer menu item.

see here:
muyguapa.org

menu item under “life” that reads “muy guapa life by amy smith”

i want to make the type bigger, but when it is bigger, it extends beyond the menu background.

thanks so much!
r