Menu Problem at 1100px approx. www.andreasebner.at

this is the CSS:

.header_color .main_menu ul:first-child > li > a {font-weight: 400; font-size: 16px; font-family:’Helvetica Neue’}
.header_color .main_menu ul:first-child > li > a:hover { color: #03558f; }
.header_color .main_menu ul:first-child > li.current_page_item > a { color:#03558f; }

.main-title a {
color: #03558f !important;
font-size: 24px !important;
}

.avia-menu {
border-right: 0px !important;
}

.iconbox_content_title {
font-size: 15px!important;
}

#footer a {
padding: 0;
}
#footer input {
margin-bottom: 0;
}

.leaflet-control-attribution.leaflet-control {
display: none;
}

@media only screen and (max-width: 767px){
.responsive #socket .sub_menu_socket {
display: block !important;
}}
@media only screen and (max-width: 767px) {
.responsive #scroll-top-link {
display: block !important;
}}

@media only screen and (max-width: 1100px) {
#mobile-advanced, #advanced_menu_toggle, #advanced_menu_hide { display: block; }
nav.main_menu { display: none; }}
#wrap_all {
position: relative !important;
}

#footer .iconbox { margin-bottom: 10px!important; }
#footer .iconbox p { margin-top: 0 !important; }
#footer .iconbox .iconbox_content .iconbox_content_title { margin: 0!important; }

#footer .mc4wp-form-fields input[type="text"] {
margin-bottom: 0 !important;
}

#header_main_alternate {
border-top-color: transparent;

i took it out. tried that before.
no change. still broken. seems to be a theme thing?!

What can i do now?