[Debt] Unused scss rules should be removed

### Current Behavior
There are certain scss rules that aren't being used anywhere, such as [this one](https://github.com/layer5io/docs/blob/929a84e14840010fee135c1135f10396ecb9de8f/assets/scss/_tax_project.scss#L143).

### Expected Behavior
Identifying and removing these unused scss rules would clean up the codebase significantly.

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#### Contributor Guide and Resources
- 📚 [Instructions for contributing to documentation](https://github.com/layer5io/docs/blob/master/CONTRIBUTING.md)
- Layer5 documentation [site](https://docs.layer5.io) and [source](https://github.com/layer5io/docs/)
- 🎨 Wireframes and [designs for Layer5 site](https://www.figma.com/file/5ZwEkSJwUPitURD59YHMEN/Layer5-Designs) in Figma [(open invite)](https://www.figma.com/team_invite/redeem/GvB8SudhEOoq3JOvoLaoMs)
- 🙋🏾🙋🏼 Questions: [Layer5 Discussion Forum](https://discuss.layer5.io) and [Layer5 Community Slack](http://slack.layer5.io)

Read CONTRIBUTING.md, then inspect assets/scss/_tax_project.scss around line 143 and search the repository for references to the SCSS rules. Remove only rules confirmed to be unused, with the documentation site’s styling still intact as the completion criterion.

Written by the indexing model from the issue text.