Adwords max CPC at keyword level

I have 1 ad-groups with max CPC set to lets say $0.30

I have few keywords inside that ad-group which are "under first page bid estimate" and I am going to increase their individual max CPC to a value which is higher then the ad-group max CPC , lets say $0.50

Question:
Do I have to also increase the entire ad-group max CPC or will the keyword level max CPC rule and be more important then the ad-group max CPC ?

Please answer with a reference link that proves your answer.

Thank you!