html 类和id 

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title></title>
        <style type="text/css">
            .cla1{
                background-color: blue;
                color: red;
                
            }
            span.red{
                color: green;
            }
            
            #sec{
                color: black;
                text-align: center;
            }
        </style>
    </head>
    <body>
        <!-- class不唯一 -->
        <div class="cla1">
            <h1>this is div_h1</h1>
            <p>text text</p>
        </div>
        
        <h1>My <span class="red">Important</span> Heading
        </h1>
        <!-- id唯一 -->
        <h1 id="sec">SecondH1</h1>
    </body>
</html>

 

posted @ 2022-02-26 18:23  lwx_R  阅读(26)  评论(0)  编辑  收藏  举报