x
<html><head><style>h1, h2, div { background-color: lightgreen;}h1 { border-block: 5px solid red;}h2 { border-block: 4px dotted blue;}div { border-block: double;}</style></head><body><h1>A heading with a solid red border in the block direction</h1><h2>A heading with a dotted blue border in the block direction</h2><div>A div element with a double border in the block direction.</div></body></html>