.dropdown-menu, .dropdown-submenu {
  margin: 0px;
}
.dropdown-submenu {
  position: relative;
}

.dropdown-submenu a::after {
  transform: rotate(-90deg);
  position: absolute;
  right: 6px;
  top: .8em;
}

.dropdown-submenu .dropdown-menu {
  top: 0;
  left: 100%;
}

.dropdown-menu:hover a.dropdown-toggle {
  display: block;
}