Waterfall headers won't work with menu

I'm trying to combine a [menu](http://www.getmdl.io/components/index.html#menus-section) with a [waterfall header](http://www.getmdl.io/components/index.html#layout-section). The problem is that the waterfall header sets overlow to hidden and the menu is broken. You can see an example here: http://codepen.io/santiagobasulto/pen/adEKry

Is there any way to fix this? (and combine both the menu and the waterfall header?)

Thanks!

Screenshot for reference: