CSS と HTML の使用に関する誤解

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<ul class="nav">
      <li><a href="/home/">Home</a></li>
      <li><a href="/about/">About</a></li>
      <li><a href="/concact/">Concact</a></li>
</ul>

<h1 class="news-head">Elastic Layout Example—View Source for the HTML and CSS</h1>
<p class="news-head">Lorem ipsum dolor sit amet.
        Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.
        Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>

<p class="news">
    <h1>Elastic Layout Example—View Source for the HTML and CSS</h1>
    <p>Lorem ipsum dolor sit amet.
        Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.
        Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
</p>

<h2> Andy wins an Oscar for his cameo in Iron Man</h2>
<p>Public and on <span class="date">Februray 22nd, 2009</span>
    By <span class="author">Harry Knowles</span>
</p>

/*大量的使用id,很难找到唯一名称混乱*/
#andy, #rich, #jeremy, #james-box, #sophie {
    font-size: 1em;
    font-weight: bold;
    border: 1px solid #ccc;
}
/*只需一个普通类替代它*/
.staff {
    font-size: 1em;
    font-weight: bold;
    border: 1px solid #ccc;
}