Open Sandbox button has a strange white border

[reekystive]

🐛 bug report

Preflight Checklist

• [x] I have read the Contributing Guidelines for this project.
• [x] I agree to follow the Code of Conduct that this project adheres to.
• [x] I have searched the issue tracker for an issue that matches the one I want to file, without success.

Description of the problem

The "Open Sandbox" button has a strange white border, which makes the visual effect of our favorite perfect project looks bad in dark mode.

To Reproduce

Use the CSS below then preview Sandbox in new tab:

:root {
  color-scheme: dark;
  background-color: #1e1e1e;
}

Link to sandbox: open-sandbox-button-dark-mode-issue

Your Environment

Software	Name/Version
Сodesandbox	0.0.318
Browser	Arc
Operating System	macOS