CSS Demo: border-block-start

border-block-start: solid;
writing-mode: horizontal-tb;
border-block-start: dashed red;
writing-mode: vertical-rl;
border-block-start: 1rem solid;
writing-mode: horizontal-tb;
border-block-start: thick double #32a1ce;
writing-mode: vertical-lr;
This is a box with a border around it.