用栅格来规范布局

样式类为:row

 

<div class="container" id="summary_container">
        <div class="row">
            <div class="col-md-4">
                <img src="image/firefox-logo-small.jpg" alt="firefox"/>
                <h2>火狐浏览器</h2>
                <p>火狐浏览器专业为大众做的免费浏览器，方便各种看片！专为你而造！</p>
                <p><a class="btn btn-lg btn-primary" href="" role="button">查看详情</a></p>
            </div>
            <div class=" col-md-4">
                <img src="image/chrome-logo-small.jpg" alt="firefox"/>
                <h2>谷歌浏览器</h2>
                <p>谷歌浏览器专业为大众做的免费浏览器，方便各种看片！专为你而造！</p>
                <p><a class="btn btn-lg btn-primary" href="" role="button">查看详情</a></p>
            </div>
            <div class="col-md-4">
                <img src="image/chrome-logo-small.jpg" alt="firefox"/>
                <h2>Safari浏览器</h2>
                <p>Safari浏览器专业为大众做的免费浏览器，方便各种看片！专为你而生！</p>
                <p><a class="btn btn-lg btn-primary" href="" role="button">查看详情</a></p>
            </div>
        </div>
        <hr/>
    </div>