border-block-style

The border-block-style CSS property defines the style of the logical block borders of an element, which maps to a physical border style depending on the element's writing mode, directionality, and text orientation. It corresponds to the border-top-style and border-bottom-style, or border-left-style and border-right-style properties depending on the values defined for writing-mode, direction, and text-orientation.
border-block-style css reference