Twitter Bootstrap Drop-down on hover

Twitter Boostrap 3, drop-down menu on hover.

 

.dropdown-menu {
    .sub-menu {
        left: 100%;
        position: absolute;
        top: 0;
        visibility: hidden;
        margin-top: -1px;
    }
    li:hover .sub-menu {
        visibility: visible;
    }
}

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

.nav-tabs .dropdown-menu, .nav-pills .dropdown-menu, .navbar .dropdown-menu {
    margin-top: 0;
}

.navbar {
    .sub-menu:before {
        border-bottom: 7px solid transparent;
        border-left: none;
        border-right: 7px solid rgba(0, 0, 0, 0.2);
        border-top: 7px solid transparent;
        left: -7px;
        top: 10px;
    }
    .sub-menu:after {
        border-top: 6px solid transparent;
        border-left: none;
        border-right: 6px solid #fff;
        border-bottom: 6px solid transparent;
        left: 10px;
        top: 11px;
        left: -6px;
    }
}