`git-checkout-pr` style is inconsistent to GitHub #4700

Please ensure:

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

Description

• git-checkout-pr use a different style from GitHub when clicking the copy button
• The button should be vertically centered

Screenshot

GitHub: <img width="362" alt="Screen Shot 2021-08-23 at 02 19 09" src="https://user-images.githubusercontent.com/44045911/130365776-caa439b3-b59a-4bbd-aaf7-806f8acee9e1.png">

Refined GitHub:

<img width="362" alt="Screen Shot 2021-08-23 at 02 19 29" src="https://user-images.githubusercontent.com/44045911/130365780-2be04d31-2678-4c37-a8e0-58e262e5260a.png">

Console errors

No response

Example URL

https://togithub.com/sindresorhus/refined-github/pull/4639

Browser(s) used

Chrome