buy now buttons

in layout settings you can choose if buy now buttons are images or css buttons

when I use css buttons i cannot change the size of the button.

upon inspecting the site I found that zencart adds the height and width style as a parameter of the button tag (its actually a span rather than a form button that most buttons use on websites)

so it looks something like this
<span class="buynow" style="height:20px; width:50px;">

since the style is injected by zencart into the tag itself it cannot be removed and since it,s in the tag itself it overrides any css rule regarding the height and width of the button.

i have tried using !important in the css sheets for the height and width property but this doe not work ether

any ideas anyone?