How do I alternate DIV colors in a while loop?

How do I alternate DIV colors in a while loop?

Let's say I have a code that looks like this:
while ($info = mysql_fetch_assoc($data_p)) {
$name = stripslashes($info['name']);
$desc = stripslashes($info['description']);
$desc = substr($desc, 0, 150);
$price = stripslashes($info['price']);
Print "<div style=\"width:600px; height:150px; border:1px solid black;
overflow:hidden\"><div style=\"height:148px; width:25%; border:1px
solid red; float:left\"><center><img src=\"".$picture."\"
height=\"120\" width=\"120\" style=\"margin-top:15px\"
/></center></div><div style=\"height:150px; width:50%; border:1px
solid blue; float:left; text-overflow: ellipsis;
padding-top:5px\"><center><font size=\"+1\"><b><a
href=\"result.php?product=".urlencode($name)."\">".$name."</b></a></font><br><br>".$desc."...</center></div><div
style=\"height:150px; width:24%; border:1px solid green;
float:left\"><center><h1>$".$price."</h1><button>Add to
Cart</button></center></div></div>";
The main DIV that is first defined in the while loop I would like to
alternate two shades of grey. So in the results it would look like light
dark light dark etc...I've tried simply repeating the echos again with a
different color but that makes duplicates of each result. Is there a way
to do this?