Horizontal
Defines the height of the horizontal gutter which runs from left to right across the sheet.
If proofs are not at the maximum height of a cell, the space between two proofs may appear larger than the specified gutter value.
Vertical
Defines the width of the vertical gutter, which runs from top to bottom down the proof. If proofs do not maximize the width of a cell, the space between two proofs may appear larger than the specified gutter value.
