In any case, well done! In North American sports, there's a push to use a similar sort of system in baseball for calling balls/strikes, I'd be curious to compare my judgement against the computer system they're testing in some minor leagues.
Not quite. Head, body and feet all count.
https://www.thefa.com/football-rules-governance/lawsandrules...
> A player is in an offside position if: any part of the head, body or feet is in the opponents’ half (excluding the halfway line) and any part of the head, body or feet is nearer to the opponents’ goal line than both the ball and the second-last opponent
> The hands and arms of all players, including the goalkeepers, are not considered.
> A player is not in an offside position if level with the: second-last opponent or last two opponents
At least the VAR people should admit that there is an inherent margin of error in the technology (camera framerate, image resolution, blur..), and offsides calls should only be made when the result is outside that (somehow quantified) margin of error.