<html>
    <head>
        <meta charset=utf-8>
        <style type="text/css">
            /*补全代码*/
            body{
                color:rgb(255,0,0);
                font-size:20px
            }
            .green{
                color:rgb(0,128,0)
            }
            #black{
                color:rgb(0,0,0)
            }
        </style>
    </head>
    <body>
        <div>红色</div>
        <div class='green'>绿色</div>
        <div id='black'>黑色</div>
    </body>
</html>