I have got one of those toilet seats that are held on to the toilet pan with
plastic fittings and screws.
The blessed seats thing keeps falling off the loo no matter how much I
tighten the screws, but today, necessity being the mother of invention, I
finally cured it.
Taking a mouse mat, I cut two squares out of it . Punched a hole in the
middle of each square, put the mouse mat between the toilet pan and the seat
brackets and tightened the screws. Bingo.... Worked brilliantly.
Ah I hear you say, you could have used rubber washers. Unfortunately the
brackets on my seat are square and not round so to get full coverage, I used
the mouse mat. Trimmed it off afterwards so no one is the wiser, except you
lot of course.