It isn’t that unusual for teams moving or renovating a stadium to sell their old seats. York City did it a few years ago and the very old wooden seats from the main stand look great. I know a few people who got themselves one or two

As the laws of the game stand it is offside, however I do feel like it should be measured from the feet. I know you can score with your head, but there is always going to be a certain amount of lean while sprinting. Arms/shoulders shouldn’t come into play because a defender on the half turn is going to have their arm out for balance as they’re turning (shown in the photo). I’d prefer feet as the point of measure, but from the current rules it is offside. Fine margins at such high speed though.