Hello Michael
The foot is basically a pentagon; is 30cm wide at the front (at the user). It extends outwards on both sides by approx. 5° on each side and 22cm to the rear. The two rear sides are 20cm long and meet behind the pillar in the point.
The widest point for me is 37cm and the deepest point is 30cm. At the front (at the user) the edge is slightly concave, i.e. slightly curved along the screen.
(I would have liked to add a picture with the dimensions, but I don't think I can).
Best regards
Stephan

36 x 29 cm (W x D)
The base is not square, so just use the two largest dimensions.
... and be happy!!! It really is a great screen 😁