Need more understanding angular material list

[Malte Kempff]

Hi 

I have following Angular code, that makes me wonder, why my material-list does not have a vertical scrollbar:

I am wondering about that, since I read somewhere, that you need those entry for the mat-list in the css-File I did:

mat-list {

  flex-grow: 1;

  border: 3px solid green;

  overflow: auto;

}

But it does not work at all as you can see in the screen shot.

Please find the files for that matter in the up/download 

Any hint is appreciated
Thanks in advance and best regards

Schumuoan