For me help this code:
nav.mega-menu li .sub-container.non-mega {
min-width: 100%;
max-width: 100%;
left: 0!important;
}
nav.std-menu .menu ul li > a, nav.std-menu .menu ul li > span.title {
padding: 10px 15px;
display: block;
margin: 0;
white-space: nowrap;
max-width: 100%;
text-overflow: ellipsis;
overflow: hidden;
}
nav.std-menu .menu ul.sub-menu {
position: absolute;
z-index: 9995;
margin: 0;
top: 80px;
left: 0;
min-width: 170%;
opacity: 0;
-moz-opacity: 0;
filter:alpha(opacity=0);
pointer-events: none;
-moz-box-shadow: 0 0 5px -1px rgba(0,0,0,.2);
-webkit-box-shadow: 0 0 5px -1px rgba(0,0,0,.2);
box-shadow: 0 0 5px -1px rgba(0,0,0,.2);
-webkit-transition: all 0.2s ease-in-out;
-moz-transition: all 0.2s ease-in-out;
-o-transition: all 0.2s ease-in-out;
transition: all 0.2s ease-in-out;
}