Fix 529: Background screen flash on reload

[sshkeda]

Please describe the changes this PR makes and why it should be merged:

I followed instructions from https://github.com/pacocoursey/next-themes#without-css-variables to fix flashing. Now instead of seeing a quick white screen flash into your eyes when you open the site, the background will stay dark.

Status

• Code changes have been tested against prettier, or there are no code changes
• I know how to update typings and have done so, or typings don't need updating

Semantic versioning classification:

• This PR changes the codebase
  • This PR includes breaking changes (methods removed or renamed, parameters moved or removed)
  • This PR changes the internal workings with no modifications to the external API (bug fixes, performance improvements)
• This PR only includes non-code changes, like changes to documentation, README, etc.

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[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you all sign our Contributor License Agreement before we can accept your contribution.
1 out of 2 committers have signed the CLA.

✅ aidenybai
❌ sshkeda
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[aidenybai]

Nice work! LGTM :)