nav.mainnavigation-menu {
    background: rgba(0, 0, 0, 0) radial-gradient(ellipse at center center , #005982 0%, #002d4b 100%) repeat scroll 0 0;
    display: none;
    height: 100vh;
    left: 0;
    margin-top: 0;
    opacity: 0;
    position: fixed;
    text-align: center;
    top: 0;
    width: 100%;
    z-index: 3;
}