No hard/heart feelings

I just want to know which one is right. whether it is hard feelings or heart feelings.

I've only heard 'hard,' meaning the opposite to 'tender.' 'No hard feelings?' = 'I hope you weren't offended.'

"Hard" in "hard feelings" means "resentful." (Merriam-Webster online)

I have no hard feelings about my last post vanishing into thin air. I think something is wrong with my computer today. Or with me.