console 命令行工具 X clear
console
<html>
  <head>
    <title></title>
    <style type="text/css">
    .strong {
     color:green;
     }

.h2 {
     color: red;
     }

.h2 strong {
     color: blue;
     }

    </style>
    </head>
  <body>
    <p>The strongly emphasized word in this paragraph is<strong>red</strong>.</p>
<h2>This subhead is also red.</h2>
<h2>The strongly emphasized word in this subhead is<strong>blue</strong>.</h2>
</body>
  </html>