​x
 
<!DOCTYPE html>
<html>
<head>
<style> 
div {
  background-color: lightgreen;
  inline-size: 300px;
  padding: 10px;
  border-block-width: 5px;
  writing-mode: vertical-rl;
  border-block-style: solid;
  border-block-color: blue;
}
</style>
</head>
<body>
​
<h2>border-block-color: blue:</h2>
<div>
  <p>当 writing-mode 属性值设置为 vertical-rl 时，受 border-block-color 属性影响的边框位于左侧和右侧。</p>
</div>
​
</body>
</html>
​