L.A.J.Schutter on "[Theme: Expound] Responsive vs Mobile : pulldownmenu not working"

I looked around a lot in all different files. This is what I found about MENU, within the RTL-stylesheet (rtl.css file):

/* =Menu
----------------------------------------------- */

.navigation-main ul {
list-style: none;
margin: 0;
padding-right: 0;
}
.navigation-main li {
float: right;
position: relative;
}
.navigation-main ul ul {
box-shadow: 0 3px 3px rgba(0, 0, 0, 0.2);
display: none;
float: right;
position: absolute;
top: 1.5em;
right: 0;
z-index: 99999;
}
.navigation-main ul ul ul {
right: 100%;
top: 0;
}

@media screen and (max-width: 600px) {
.menu-toggle,
.main-small-navigation ul.nav-menu.toggled-on {
display: block;
}

.navigation-main ul {
display: none;
}
}

.main-small-navigation ul ul a {
padding-right: 60px;
}
.main-small-navigation ul ul ul a {
padding-right: 80px;
}
.main-small-navigation ul > .current_page_item,
.main-small-navigation ul > .current-menu-item {
background: #117bb8;
}
.navigation-main {
background: #3a3a3a;
}
.navigation-main ul {
margin: 0 30px;
}
.navigation-main a {
color: white;
padding: 10px;
position: relative;
}
.navigation-main li {
background: #3a3a3a;
}
.navigation-main li:hover {
background: #474747;
}
.navigation-main ul > .current_page_item,
.navigation-main ul > .current-menu-item,
.navigation-main ul > .current-post-ancestor,
.navigation-main ul > .current-menu-ancestor,
.navigation-main ul > .current-menu-parent,
.navigation-main ul > .current-post-parent {
background: #117bb8;
}
.navigation-main ul > .current_page_item:hover,
.navigation-main ul > .current-menu-item:hover,
.navigation-main ul > .current-post-ancestor:hover,
.navigation-main ul > .current-menu-ancestor:hover,
.navigation-main ul > .current-menu-parent:hover,
.navigation-main ul > .current-post-parent:hover {
background: #138bcf;
}
.navigation-main ul > .current_page_item:hover a:after,
.navigation-main ul > .current-menu-item:hover a:after,
.navigation-main ul > .current-post-ancestor:hover a:after,
.navigation-main ul > .current-menu-ancestor:hover a:after,
.navigation-main ul > .current-menu-parent:hover a:after,
.navigation-main ul > .current-post-parent:hover a:after {
border-top-color: #138bcf;
}
.navigation-main ul > .current_page_item ~ .current_page_item a,
.navigation-main ul > .current-menu-item ~ .current-menu-item a,
.navigation-main ul > .current-post-ancestor ~ .current-post-ancestor a,
.navigation-main ul > .current-menu-parent ~ .current-menu-parent a,
.navigation-main ul > .current-post-parent ~ .current-post-parent a {
background: #3a3a3a;
}
.navigation-main ul > .current_page_item ~ .current_page_item a:hover,
.navigation-main ul > .current-menu-item ~ .current-menu-item a:hover,
.navigation-main ul > .current-post-ancestor ~ .current-post-ancestor a:hover,
.navigation-main ul > .current-menu-parent ~ .current-menu-parent a:hover,
.navigation-main ul > .current-post-parent ~ .current-post-parent a:hover {
background: #474747;
}
.navigation-main ul > .current_page_item a:after,
.navigation-main ul > .current-menu-item a:after,
.navigation-main ul > .current-post-ancestor a:after,
.navigation-main ul > .current-menu-parent a:after,
.navigation-main ul > .current-post-parent a:after {
content: '';
font-size: 0px;
line-height: 0%;
width: 0px;
border-top: 6px solid #117bb8;
border-left: 6px solid transparent;
border-right: 6px solid transparent;
position: absolute;
bottom: -6px;
left: 50%;
margin-left: -6px;
z-index: 9995;
}
.navigation-main ul > .current_page_item ~ .current_page_item a:after,
.navigation-main ul > .current-menu-item ~ .current-menu-item a:after,
.navigation-main ul > .current-post-ancestor ~ .current-post-ancestor a:after,
.navigation-main ul > .current-menu-parent ~ .current-menu-parent a:after,
.navigation-main ul > .current-post-parent ~ .current-post-parent a:after,
.navigation-main ul ul li a:after {
content: '';
border: none !important;
}
.navigation-main ul ul {
margin: 0;
top: 40px;
z-index: 9990;
}
.navigation-main ul.social {
padding: 0;
list-style: none;
float: right;
margin-right: 36px;
/* -4px bc of padding */
}
.navigation-main ul.social li:hover {
background: none;
}
.navigation-main ul.social li a {
width: 24px;
padding-left: 0;
padding-right: 0;
background: url('../images/social.png') 0 50% no-repeat;
color: transparent;
text-indent: -9999px;
padding-left: 4px;
opacity: 0.2;
}
.navigation-main ul.social li a:hover {
opacity: 0.5;
}
.navigation-main ul.social li.twitter a {
background-position: -205px 50%;
}
.navigation-main ul.social li.facebook a {
background-position: -12px 50%;
}
.navigation-main ul.social li.feed a {
background-position: -108px 50%;
}
.navigation-main ul.social li.vkontakte a {
background-position: -59px 50%;
}
.navigation-main ul.social li.google-plus a {
background-position: -157px 50%;
}
.site-header .menu-toggle {
background: #3a3a3a;
color: white;
font: 13px/20px "Helvetica Neue", Helvetica, Arial, sans-serif;
font-weight: 300;
padding: 10px 22px;
margin: 0;
}
.site-header .menu-toggle:hover {
background: #474747;
}
.site-header .menu-toggle:before {
content: '\2261';
font-size: 14px;
margin-right: 10px;
}