Make sidebar sticky and collapsed on sass docs

[dingo-d]

Describe your feature request

Currently clicking on any of the links in the sidebar here: https://infinum.github.io/eightshift-docs/sass will scroll you to that part of sass docs, but the sidebar stays at the top, which is not ideal from a UX point of view.

Describe the solution you'd like

Having the headings collapsed would allow us to have this sidebar sticky on the desktop resolutions when scrolling the content.

Screenshots, screen recording, code snippet

No response

Environment info

• N/A

Please confirm that you have searched existing issues in this repo.

Yes

Please confirm that you have searched in our documentation and couldn't find the answer.

Yes

[iruzevic]

done