Feature/six sidebar expose container part

[flamenkito]

🔗 Linked issue

❓ Type of change

• 📖 Documentation (updates to the documentation, readme or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Expose container part in six-sidebar for styling.
Get rid of width parameter in favor of --width CSS variable.

📝 Checklist

• I have linked an issue or discussion.
• It's submitted to the main branch
• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)
• I have updated the documentation accordingly.
• All tests are passing
• New/updated tests are included
• I have updated the "upcoming" section inside docs/changelog.md explaining the changes I contributed

If adding a new feature, the PR's description includes:

• A convincing reason for adding this feature (to avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it)

Other information:

[colinscz]

This would mean we have a breaking change, I guess we could include this in the release which also targets node 18 and above but not before.

cc: @ibirrer

[stefanrufer]

@flamenkito
Suggestion: If the PR is made compatible to V4, we can merge it right away (leave width and just add --width, don't drop inputs. Otherwise we would wait for V5 with this PR.

[colinscz]

@flamenkito is this still an issue for you?
If so, would you please rebase your branch to the latest version of main?

We are preparing v5 on main and this could potentially land in one of the next beta releases for v5. (Need to sync with the team in the next weekly)

Thx!

[colinscz]

Closing this, since it was not updated and seems to be not a priority. Please reopen a new pull request in the future or bring it up in the regular sync.