subnavigation_left — main column
colPos 0, span 9 → 765px, order: 2. The subnavigation column is not a content column — it is rendered by the Navigation/Subnavigation partial and spans 3 → 255px, ordered first.
The subnav column used to carry a grey debug tint, rgba(204, 204, 204, .2), which rendered on the live site. It is gone.