dropdown style broken on Safari

[fraserxu]

Hi, the style of dropdown menu is broken on Safari. http://callemall.github.io/material-ui/#/components/menus

My browser:

User-Agent  Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10) AppleWebKit/600.1.25 (KHTML, like Gecko) Version/8.0 Safari/600.1.25

Before selecting:

While selecting:

After selecting: