horizontal
This is a convenience function that opens a context (BorderContext) to specify the border styles for both vertical sides of a block at once, that is the right and left hand side via `border-left-{property}` and `border-right-{property}` CSS properties.
The actual styling is then done within the BorderContext using the specific topic functions of it.
See also
Parameters
value
extension function parameter to open the BorderContext as scope of the functional expression in order to use its specific styling functions.