PR-table-related CSS improvements.

[robinlinden]

Increase font-size in PR-table. Decrease margins and padding around content. Center state.

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This change is 

[GrayHatter]

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Reviewed 1 of 1 files at r1. Review status: all files reviewed at latest revision, all discussions resolved, some commit checks failed.

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[iphydf]

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Reviewed 1 of 1 files at r1. Review status: all files reviewed at latest revision, all discussions resolved.

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[cebe]

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Reviewed 1 of 1 files at r1. Review status: all files reviewed at latest revision, all discussions resolved.

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Comments from Reviewable