Improve theme readability and style

[kitsunekyo]

Description

The visual presentation of the current docs does not match the quality of the project, so this PR aims to improve that.

issues:

• Sidebar is barely readable and fails accessibility contrast checks
• there's a ton of unnecessary customizations like custom header that would make implementing the built in docusaurus search and other features more complicated than necessary
• Aside, table of contents and content are not properly aligned at the top
• mobile rendering looks broken

Before:

After:

Changes:

• use the default docusaurus header instead of a custom header implementation
• use dark docusaurus theme
• change primary color to thatopencompany brand color
• removed custom layout blocks for better use of screen space
• made moving gradient more subtle
• many other minor styling improvements, and minor refactorings to prepare for future docusaurus 3 upgrade

---

What is the purpose of this pull request?

• [ ] Bug fix
• [ ] New Feature
• [ ] Documentation update
• [x] Other

Before submitting the PR, please make sure you do the following:

• [x] Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• [x] Follow the Conventional Commits v1.0.0 standard for PR naming (e.g. feat(examples): add hello-world example).
• [x] Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• [ ] Ideally, include relevant tests that fail without this PR but pass with it.

[vercel[bot]]

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Name	Status	Preview	Comments	Updated (UTC)
docs	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Apr 24, 2024 1:27pm

[kitsunekyo]

vercel preview deployments seem to be broken and always use the main branch. checkout locally and build / yarn dev to see the updated docs