Single rule handwriting paper

The single-rule style is a genuinely different render path from the guided papers above it — it draws one plain line per row with no baseline, midline, or topline sitting underneath it. That makes it structurally identical to ordinary notebook paper, not a stripped-down version of the dotted or primary styles.

This is where a child lands after the dotted mid-line stops being needed — letter height is now self-judged, not line-guided. It's the plainest paper in the set: enough structure to keep a line of writing level, and nothing else competing for the child's attention.