ul.sub-menu {
  display: none;
  position: absolute;
  left: 100%;
  top: 0;
  background: #fff;
  padding: 10px 0;
  list-style: none;
  border: 1px solid #ddd;
}

.menu-item-has-children:hover > .sub-menu {
  display: block;
}

.menu-item {
  position: relative;
}

.menu-item a {
  display: block;
  padding: 8px 15px;
  color: #333;
  text-decoration: none;
}

.menu-item a:hover {
  background: #f2f2f2;
}