Look for the plastic shims with cut-outs that fit neatly around the screws that hold your hinges in place in the door frame. A 10-pack of KS Hardware 4-inch door hinge shims in black PVC is about ...

You can conceal them behind door hinges to get just the right swing, ... Prevent rocking with the judicious use of plastic plumbing shims: Keeney Keeney Toilet Leveling Shims (8 Pack) $10 at Amazon.