#button li {
  list-style: none;
  margin: 0.5em;
}
#button li a {
  color: #000;
  text-decoration: none;
  display: block;
  border-top: #ccc solid 3px;
  border-left: #ccc solid 3px;
  border-bottom: #000 solid 3px;
  border-right: #000 solid 3px;
  width: 10em;
  background: #eee;
  text-align: center;
}
#button li a:hover {
  border-top: #000 solid 3px;
  border-left: #000 solid 3px;
  border-bottom: #ccc solid 3px;
  border-right: #ccc solid 3px;
  background: #666;
  color: #fff;
}