<!DOCTYPE html><html><head>    <meta charset="utf-8">    <title>CSS 分组和嵌套</title>    <style>
    h1,
    h2,
    p {
     
    .marked p {
        border-top-style: dotted;
        border-right-style: solid;
        border-bottom-style: dotted;
        border-left-style: solid;    }
    
    p.two {
        border-style: solid;
        border-width: medium;
        border-color: #98bf21;    }
    
    p.three {
        border-style: solid;
        border-width: 1px;    }    </style></head>
    
    
        color: white;    }    <div class="marked">        <p>this is p</p>    </div></body></html>