console 命令行工具 X clear
console
<!DOCTYPE html>
<html>
   <head>
    <meta charset="UTF-8"/>
    <title></title>
    <style type="text/css">
    p{
        color:red;
    }
    </style>
</head>
<body>
    <p>实验楼</p>
</body>
</html>
<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <title></title>
    <style type="text/css">
      p {
        color: red;
      }
      .bgc {
        background-color: yellow;
      }
    </style>
  </head>
  <body>
    <p class="bgc">实验楼</p>
  </body>
</html>
<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <title></title>
    <style type="text/css">
      p {
        color: red;
      }
      .bgc {
        background-color: yellow;
      }
      .one {
        font-size: large;
      }
    </style>
  </head>
  <body>
    <p class="bgc">实验楼</p>
    <p class="bgc one">我爱学习</p>
  </body>
</html>