Dashboard groupe open/close pre NRv2.20

My Dashboard does not open/close groups with this sample.

It says that open/close works since 2.20. I have 2.1.6.
Can I close my groups with CSS somehow like inside the dashboard-group preference window?

Bildschirmfoto 2022-11-21 um 15.10.27

Can you not upgrade so that you have 2.20 or later?

No, that's why I am asking for CSS workarounds...