Is this optimal for resizing text on all mobile devices?

<head>
<style type="text/css">
 @media only screen and (max-width: 600px) {
    .bigbunny {
      font-size:20px !important;
      line-height:125% !important;
}
</style>
</head>
<body>
<span style="font-size: 16px; font-weight: normal; font-family: Arial; margin: 0 0 10px; padding: 0;" class="bigbunny">Blah, blah, blah, yada, yada, yada</span>

thanks
jas