A colour for each edge. An edge left out falls back to borderColor's single-string form, or to
black when there is none.
Where two edges of different colours meet at a corner, the corner is split between them — the
same join CSS makes, so a card with one accent edge does not smear that colour round the bend.
A colour for each edge. An edge left out falls back to
borderColor's single-string form, or to black when there is none.Where two edges of different colours meet at a corner, the corner is split between them — the same join CSS makes, so a card with one accent edge does not smear that colour round the bend.