Mobile Menu Styling - 7.1

The new header edting format seems very odd - looks like there have been a few options removed? We're trying to style the mobile menu icon which you used to be able to do (thickness etc) but that all seems to have disappeared?

Does anyone know what's happened/got a fix? Rather do it through default options than have to add CSS for something you didn't used to need to for.

Thanks so much! That was well hidden.