Investigate whether a separate homepage.css would be optimal

[philwareham]

At the moment we have a single CSS file that is used across the .com site, docs site, themes site and plugins site. While this is good for caching there may be a valid case for having a separate CSS file that is used on homepages only.

This would allow us to target elements that only appear on the homepage(s) and remove all other non-essential selectors from that file. Vice-versa, the homepage-only CSS selectors would not pollute the other pages of the site.

Homepage-only elements:

• Canvas element on .com site.
• The 'features' sections, with illustrations.
• The mini blog banner.
• Site showcase teaser.
• Ads.

Have to weight up the benefits against cons such as having to cache two CSS files, maintainability, etc. Should be fairly straightforward due to our modular Sass files.

This would help us achieve 100 mobile score on PageSpeed Insights/Lighthouse (currently sitting at 99 due to flagged unused CSS).