ul#main_menu_acc, ul#main_menu_acc ul {
  list-style-type:none;
  margin: 0;
  padding: 0;
  width: 15em;
}

ul#main_menu_acc a {
  display: block;
  text-decoration: none;	
}

ul#main_menu_acc li {
  margin-top: 1px;
}

ul#main_menu_acc li a {
  background: #333;
  color: #fff;	
  padding: 0.5em;
}

ul#main_menu_acc li a:hover {
  background: #000;
}

ul#main_menu_acc li ul li a {
  background: #ccc;
  color: #000;
  padding-left: 20px;
  font-size:12px;
}

ul#main_menu_acc li ul li a:hover {
  background: #aaa;
  border-left: 5px #000 solid;
  padding-left: 15px;
}