The button element has a class, but other elements has also influence on the visual look of the button. Here are all css attributes from one button (by the Firebug):
.large.awesome, .large.awesome:visited
{ font-size:14px; padding:8px 14px
9px; }
.awesome, .awesome:visited,
.medium.awesome,
.medium.awesome:visited {
font-weight:bold; line-height:1;
text-shadow:0 -1px 1px rgba(0, 0, 0,
0.25); }
.awesome, .awesome:visited {
-moz-border-radius:5px 5px 5px 5px;
-moz-box-shadow:0 1px 3px rgba(0, 0, 0, 0.5);
background:url("/images/alert-overlay.png")
repeat-x scroll 0 0 #222222;
border-bottom:1px solid rgba(0, 0, 0,
0.25); color:#FFFFFF; cursor:pointer; display:inline-block;
position:relative;
text-decoration:none; }
a { outline:0 none; }
h1, h2, h3, h4, h5, h6, p, blockquote,
pre, a, abbr, acronym, address, cite,
code, img, small, strike, sub, sup,
tt, dd, dl, dt, li, ol, ul, fieldset,
form, label, legend, button, table,
caption, tbody, tfoot, thead, tr, th,
td { border:0 none;
font-family:inherit;
font-style:normal; margin:0;
text-align:left; }