`{.left}` | Secondary headers (`##`) | Define start of left column | `## {.left}`, `## Text {.left}`
`{.center}` | Secondary headers (`##`) | Define start of central column (optional) |
`{.right}` | Secondary headers (`##`) | Define start of right column |
`{.mid}` | Slide headers (`#`) or secondary headers (`##`) | Vertically centers columns. Can be assigned to the slider header for all columns or to individual columns. | `# Slide header {layout="columns" .mid}`, `## {.right .mid}`
`{.mid}` | Slide headers (`#`) or secondary headers (`##`) | Vertically centers columns. Can be assigned to the slider header for all columns or to individual columns. | `# Text {layout="columns" .mid}`, `## {.right .mid}`
