`find-file-buffer` style inconsistent to GitHub #4768

Please ensure:

• The bug is caused by Refined GitHub. It doesn't happen if I disable the extension.

Description

GitHub's separator (/) is darker (see screenshots below).

Screenshot

<img width="515" alt="Screen Shot 2021-09-09 at 01 20 13" src="https://user-images.githubusercontent.com/44045911/132556514-6ddd2515-0acf-4f58-8f28-f58e4a529b88.png"> <img width="514" alt="Screen Shot 2021-09-09 at 01 20 35" src="https://user-images.githubusercontent.com/44045911/132556517-45f9c754-cf51-478a-9203-7177021b38cc.png">

Console errors

No response

Example URL

https://github.com/sindresorhus/refined-github

Browser(s) used

Chrome