UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:62.0) Gecko/20100101 Firefox/62.0

Steps to reproduce the problem:
1. Open the test case in Chromium Canary (71.0.3572.0) or any version since at least Chrome 49.

What is the expected behavior?
The color of 'before' and 'after' should be red.

What went wrong?
The properties on the ::after and ::before pseudo-elements are not applied.

Did this work before? No 

Does this work in other browsers? Yes

Chrome version: 71.0.3572.0  Channel: canary
OS Version: 10.0
Flash Version: 

 - The problem do not occur if the custom property is set on ::backdrop or ::first-letter.
 - Styles defined on ::first-line are correctly applied.
 - Define a custom property on a pseudo element is usefull to prevent its inheritance.