p标签在div中水平垂直居中且文本左对齐

<!DOCTYPE html>

<html>

    <head>

        <meta charset="UTF-8">

        <title></title>

        <style>

            *{margin: 0;padding: 0}

            .box{width:800px;height:100px;background:#ccc;text-align: center}

            .box p {margin:0;padding:0;display: inline-block;vertical-align: middle;text-align: left}

            #liu_area{display: inline-block;height:100%;vertical-align: middle;}

            #p_span{display: block}

        </style>

    </head>

    <body>

        <div class="box">

            <p>

                <span id="p_span">第一行</span>

                <span id="p_span">第二行</span>

            </p>

            <span id="liu_area"></span>

        </div>

    </body>

</html>

　　效果图如下：