Issue with creating a tree with lines in HTML by modifying the Angular material Tree

I try to create a Tree with lines using the Angular material tree component.
The goal is to have a Tree with lines in order to see the sources of each Tree leaf. As you will able to see in the stackblitz i just adding some element to show the border for each node

I almost got it to work, but i have this issue as you can see here with the group lines, since the lines should appear the same as the root:

Should be like this:

Any help solving this issue will be highly appreciat.