You are not calculating your sizes properly. I remade your top picture at single-pixel size:
The "under" is 83 pixels wide, not 82.
The "progress" is 79 pixels wide from first yellow to last yellow. You'll need to choose which end has the extra space:
- whether that 1 px bar comes before each progress bar (in which case, there needs to be extra 1 pixel space before first yellow)
- or after each progress bar (in which case, there needs to be extra
1 pixel space after last yellow)
in order for it to be the 80 pixels, which can be divided by 4 for each step.