CSS border-block-start-width Property - Playground Example

<!DOCTYPE html>
<html>
<head>
<style type="text/css">
.box {
  border-block: 5px dashed;
  border-block-color: green;
  border-block-start-width: 5px;
  border-block-start-color: red;
  border-block-start-style: dashed;
  writing-mode: vertical-rl;
}
</style>
</head>
<body>
<div class="box">
  This is a box with a border.
</div>
</body>
</html>