.dropdown-submenu {
    position: relative;
}

    .dropdown-submenu > .dropdown-menu {
        top: 0;
        left: 100%;
        margin-top: -6px;
        margin-left: -1px;
        -webkit-border-radius: 0 6px 6px 6px;
        -moz-border-radius: 0 6px 6px;
        border-radius: 0 6px 6px 6px;
    }

.dropdown:hover > .dropdown-menu {
    display: block;
}

.dropdown-submenu:hover > .dropdown-menu {
    display: block;
}

.dropdown-submenu > a:after {
    display: block;
    content: " ";
    float: right;
    width: 0;
    height: 0;
    border-color: transparent;
    border-style: solid;
    border-width: 5px 0 5px 5px;
    border-left-color: #ccc;
    margin-top: 5px;
    margin-right: -10px;
}

.dropdown-submenu:hover > a:after {
    border-left-color: #fff;
}