[Little Bit]

That is a common problem. Some of us have had good success with the washable pee pads. They are more absorbent than the paper so if it is near the edge it usually is absorbed back up into the pad rather than off of it. Another idea is to put a washable pee pad (which is bigger than the disposables) under your disposable pad and it will absorb any run off.

The shower curtain liner is good, but because it is not absorbent when you try to move it to clean it the pee will run off of it onto the floor. I recommend something absorbent and waterproof.