The following lines should always be light on the left and bold on the right and should all be identical (assuming your font only has two font weights).
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold
lightbold