Styling not in the slide out menu

Hi i use the main navigation and a slide menu. but when I style the main navigation it also style the slide out menu.

/* Menu | line */
@media (min-width: 769px) {
.inside-navigation .main-nav > ul > li:not(:last-child) {
position: relative;
}

.inside-navigation .main-nav > ul > li:not(:last-child) > a:after {
content: "";
height: 20px;
width: 3px;
background: #000;
display: block;
position: absolute;
right: 0;
top: 50%;
margin-top: -10px; /* half of your height */
}

I dont want this css in my slide out menu