Wrapper styling

[noah-potter]

https://github.com/dmtrKovalenko/material-ui-pickers/blob/c5e6076ae88adf2a1bf8ed85f2ee255d93717f60/lib/src/wrappers/ModalWrapper.jsx#L75

I don't see any hooks to style this. I'm willing to open a PR to add this. Thoughts?

[dmtrKovalenko]

Oh, it would be replaced with fragment in the next release.

[dmtrKovalenko]

#129

[cherniavskii]

Actually somehow I missed that div and didn't replace it with Fragment.
@noah-potter would you like to submit a PR to fix this?

[cherniavskii]

Closed by #141