feat(item-divider): add inner padding CSS variables

[corollari]

Pull request checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)
• Build (npm run build) was run locally and any changes were pushed
• Lint (npm run lint) has passed locally and any fixes were made for failures

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

Issue Number: fixes #18484

What is the new behavior?

It solves: #18484

Does this introduce a breaking change?

• Yes
• No

Other information

All credit goes to @brandyscarney, I just implemented the solution she proposed on #18484

[liamdebeasi]

Hey there,

Just wanted to mention a couple things before we merge:

1. Since these are new CSS variables, we need to document them (This will make this PR a feature instead of a bug fix).
2. The variables need to be initialized before we can use them. You can just initialize them to 0.

Can you make these changes? I can take another look after. Thanks!

[corollari]

Edit: Nevermind, just solved my question.

[corollari]

@liamdebeasi Just applied the changes you requested. Not sure if I should document the variables in a different way, right now it feels very copy-pasty.

[brandyscarney]

Thank you @corollari! I added a few small changes. I'll let Liam take another look, but looks good to me! 🙂

[corollari]

@brandyscarney cool, it seems I forgot to build the documentation.
Also, given that this is now a new feature, should I change the commit messages? or is that not needed because of the pre-merge squash?

[brandyscarney]

@corollari It's not needed, we'll update it on squash & merge. Thank you though!

[brandyscarney]

Thanks again! 🙂

[corollari]

Kudos for the awesome handling of this PR 😄