The idea
list-style-position decides whether the marker sits *outside* the item's box (in the list's padding) or *inside* it (as the first thing in the content). The default is outside, which is why lists ship with 40px of left padding. Move the marker inside and reclaim that padding.
This level needs list-style-position — moving the marker inside is the point, and the padding change is what makes the shift measurable.