Gantt not rendering in angular Dialog Box

I’m having trouble parsing data to show gantt in angular material dialog box. We have professional version 6.3.7.
I don’t know if this is a bug in library or it has something to do with styles of angular material or something.

I’m getting this render:

I have been struggling with this for few hours now and would really appreciate your help.

Cheers, Blaž

Fixed the problem with right css file import. Sorry for bad post.