设置左边框的样式 - 在线编辑器

          <!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <style>
    p {
      border-style: solid;
      border-left: thick double #ff0000;
    }
  </style>
</head>

<body>
  <p>This is some text in a paragraph.</p>
</body>
</html>
        