On 21 Jan, 13:26, neppyworker
wrote:
I'm trying to have a vertical inside border in one cell, and that choice does
not seem to be available, i.e., it's grayed out on the borders box. Why is
this?

The inside border option refers to when you are working with a range
of cells. If you selected A1:B3, and chose the inside border option,
the broder would be placed between columns A and B, and between rows 1
and 2 and 2 and 3. The only "inside" border that you can put into a
single cell is the diagonal one.