Add MacOS titlebar buttons

[whotookzakum]

Change the minimize/maximize/close buttons to mimic MacOS. Optional code for top left placement (enabled by default), and works well with expanded/collapsed sidebar on the default theme with default sizes.

[whotookzakum]

Example expanded/collapsed sidebar

[r-u-s-h-i-k-e-s-h]

Hey,
Thank you for taking the time to contribute to the repository! 🙌

I noticed that the format of the snippet in your pull request doesn't quite match the structure used in the rest of the repository. To maintain consistency, could you please update the file to follow this format?

↪[Collection](Collection.md)

# Title of the CSS Snippet

---
- author:: [Your Name or the original author's name]
- source:: [Link to the source, if applicable]
---

cover:: [Image or screenshot showing the changes]

```css
Your CSS code here