For regular hits (no crit/type)

under 100 dmg - grey

100 - 999 dmg - yellow

1k+ dmg - red

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For crits, no elemental weakness

under 100 dmg - yellow

100 - 999 dmg - red

1k+ dmg - blue

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For elemental weakness

under 100 dmg - yellow (not 100% certain on this one)

100+ dmg - blue

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For both crit and elemental weakness, bolded blue (bigger text size)