vertical bars descendant bug

[krapbucket]

I am currently using VerticalFox v1.4.1 and Sidebery v5.2.0.

Observed behavior: When I configure Sidebery using VerticalFox's sidebery_style.css file, the vertical bars that indicates descendant tabs have an extra bar. (reference first image below)

Expected behavior: I should not see an extra vertical bars (reference second image below)

Image showing Sidebery configured with VerticalFox's sidebery_style.css file showing 3 vertical lines

Image showing Sidebery NOT configured with VerticalFox's sidebery_style.css file showing 2 vertical lines. This is the behavior I like to see.

Please let me know if this is by design or if this is a bug.
If this is by design, can you please tell me how to update the sidebery_style.css so I can remove the extra vertical bar?

Thank you for creating VerticalFox.