Closed and open issues have different border color

Summary

When looking at the issue list for both open and closed issues the dividers between the list items do not have the same color.

Steps to reproduce

1. Go to the issue list and include open and closed issues.
2. Notice that list items for closed issues have a darker bottom border. See screeshot.
3. Open the developer tools to see that .issue.closed uses border-color: #dbdbdb while .issue (or rather the <li>) uses border-color: #f0f0f0.

What is the expected correct behavior?

Both list items for open and closed issues should use the same divider color.

Output of checks

This bug happens on GitLab.com