has disappeared “:before” element before row after update from 2.5.0 to 2.5.1

I have shape before row added in css. You can see it on this website: http://winda-serwis.pl/ I mean this triangle: https://www.screencast.com/t/br2KGTJw
When I copied this website and upgrade plugin to version 2.5.2 this shape dissapeared, here you can look the copy: http://zdolnelapy.pl/projekty/szambo/
There is no shape and I don’t know why. I used WP Rollback plugin and on version 2.5.0 shape is back.

Could you please give me some advice what should I do, please?

Regards
Daniel