Chrome doesn't want to display CSS block

Hi everyone, I have a little problem, chrome does not want to display the div block.

For firefox, for opera and even for IE, it works well, for chrome - no. Where could the problem be?

CSS

div#content div.ad_box{
float: left;
width: 247px;
height: auto;
border-radius: 4px;
background: #646d6e;

}

HTML

<div class="ad_box">
        <div style="text-align: center;">
            <img src="style/style_images/ad_2.jpg" alt="AD1" />
        </div>
 </div>