There's a clear difference between "I like your new haircut" which I agree is not sexual harassment and MILF: Mother I'd Like to Fuck (which is just slightly above calling your coworker slut). The second sentence is sexual harassment.
^ IIRC in California managers (as company representatives) are personally liable if they knew of the harassment and didn't take corrective action.
OP needs to lawyer up, deal with this, and address harassment more broadly in the company. Sucks to deal with... but is mandatory training for all medium-to-big companies.