Replace polished dependency with CSS relative color syntax and color-mix

[askoufis]

Since the release of Safari 18, relative color syntax and color-mix have adequate browser support and should be bug-free. This means we can safely replace polished with native CSS.

polished was only used at build-time, so this doesn't affect bundle size at all.

I checked all the colors affected by these changes. In most cases, the colors are identical (when converted to rgb), with a few having slightly different values, e.g. the blue channel increases by 1. I think this is acceptable.

Additionally, usage of rgba was replaced with rgb as rgba is considered legacy and rgb is recommended over it.

[changeset-bot]

🦋 Changeset detected

Latest commit: fd1898a

The changes in this PR will be included in the next version bump.

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playroom	Patch

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