A gram close in is worth less than a gram far out. That is the whole of it.
Pick one up, then click a notch on the beam. Click a weight already on the beam to take it off again.
The beam does not weigh anything — it measures moments. What each weight
contributes is its mass multiplied by how far along the beam it sits: moment = mass ×
distance. Ten grams at notch two and four grams at notch five are the same thing to this
beam, which is why a small weight far out can hold down a large one near the pivot, and why a
steelyard can weigh a pig with a fist-sized counterweight.
The tilt is not decoration either. The beam is integrated as a real pendulum: its own centre of mass hangs a little below the pivot, so it swings back towards level and overshoots, and it settles where the unbalanced moment and that restoring pull cancel out. Load one end heavily and it slams to the stop; load it nearly right and it hunts about for a while before it makes up its mind.
Six tasks, then it stays out of your way. Nothing here needs an account or leaves the browser.