2_columns — main column
Main content, colPos 0, span 9 of 12. Must measure 765px at a 1280px viewport, with a 60px gutter to the column on its right.
Content in here starts flush with the column edge. It used to be inset 15px by a hardcoded .frame-inner padding that applied to this layout family only, so text in a sidebar layout did not line up with text anywhere else on the site.
Secondary column
colPos 2, span 3 of 12 → 255px. This is the width Figma’s ECRIN sidebar measures exactly.