[Debt] scss rules targetting bootstrap rules should be removed

### Current Behavior
Targetting bootstrap classes to write custom styles is a footgun. Lots of footguns in the codebase like [this](https://github.com/layer5io/docs/blob/929a84e14840010fee135c1135f10396ecb9de8f/assets/scss/_footer_project.scss#L174).

### Expected Behavior
Write better style rules.

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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)

Start with assets/scss/_footer_project.scss around line 174, then search the SCSS files for custom rules targeting Bootstrap classes. Identify the affected styles and replace those selectors without changing the intended appearance; done means the Bootstrap-targeting rules are removed and the site styling still works.

Written by the indexing model from the issue text.