have you tried doing this ?
<form action="**************************cgi-bin/webscr" method="post">
<input type="hidden" name="cmd" value="_donations">
<input type="hidden" name="business" value="xxx@yyy">
<input type="hidden" name="lc" value="US">
<input type="hidden" name="no_note" value="0">
<input type="hidden" name="currency_code" value="USD">
<input type="hidden" name="bn" value="PP-DonationsBF:btn_donateCC_LG.gif:NonHostedGuest">
<input type="image" src="https://www.paypalobjects.com/en_US/i/btn/btn_donateCC_LG.gif" border="0" height="x" width="y" name="submit" alt="PayPal - The safer, easier way to pay online!">
<img alt="" border="0" src="https://www.paypalobjects.com/en_US/i/scr/pixel.gif" width="1" height="1">
</form>
either this,or modify your css file as a last resort