Prefix f-b

oh-flex currently only supports border weights up to 2px and colors of primary, the default light, and white

All
f-b

Top
f-b-t

Bottom
f-b-b

Left
f-b-l

Right
f-b-r

All
f-b-white

Top
f-b-t-white

Bottom
f-b-b-white

Left
f-b-l-white

Right
f-b-r-white

Border Width
f-b-2px

Primary
f-b-primary

Source: _border.scss, line 3