adjusting width of google plus 1 button

I am trying to figure out how to modify the width of the Google plus 1 button...

In the documentation it says you can set a width.

Currently, when I examine the element using Firebug... it says the width is set to 90px, which I would like to set to 70px... is that possible?

    <!-- Place this tag where you want the +1 button to render -->
    <g:plusone size="medium"></g:plusone>

    <!-- Place this render call where appropriate -->
    <script type="text/javascript">
      (function() {
        var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true;
        po.src = 'https://apis.google.com/js/plusone.js';
        var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s);
      })();
    </script>

You can pick from a couple of height settings at the code generator, but you can't pick an arbitrary size value.