table td a#iriguchi,
 table td a#deguchi {
  display: block;
  width: 146px;
  height: 52px;
 }
 
 table td a#iriguchi { background:url(/img/button_in.gif); }
 table td a#iriguchi:link { background-position: top left; }
 table td a#iriguchi:hover { background-position: top right; }
 
 table td a#deguchi { background:url(/img/button_out.gif); }
 table td a#deguchi:link { background-position: top left; }
 table td a#deguchi:hover { background-position: top right; }