Fix dark mode for blog post

[gsmet]

If you are updating a guide, please submit your pull request to the main repository: https://github.com/quarkusio/quarkus/tree/main/docs/src/main/asciidoc

[gsmet]

@insectengine I pushed an emergency fix because of the following:

I will let you decide if it was the right thing to do :).

[github-actions[bot]]

🎊 PR Preview 9ab16aca07b45f87838b9b94468f58fb9ccf32bb has been successfully built and deployed to https://quarkus-site-pr-2005-preview.surge.sh

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