April 2028 has 30 days. The 1st falls on a Saturday and the 30th on a Sunday, so the grid runs to 6 rows.
No US federal holiday falls in April 2028. The holidays layout still marks nothing this month, so it prints the same as the blank sheet.
Holiday names print inside the day cell, wrapped to fit rather than running across the rule into the next day.
The week runs Sunday to Saturday, the usual US arrangement.