.button a{
font: bold 14px Verdana, Arial, sans-serif;
text-decoration: none;
text-indent: 24px;
color: #FFFFFF; 
background: url( mybutton.png );
display: block;
width: 140px;
line-height: 21px;
height: 21px;
}
.button a:hover{
background-position: 0px -24px;
text-decoration: none;
color: #FFFFFF;
}