.third {
    display:none;
    position: absolute;
    left: 100%;
    top: 0;
    width: 120%;
    background: #0176d5;}

.second-nav>li:hover .third {
    display:block;}

.fourth-nav {
    display:none;
    position: absolute;
    left: 100%;
    top: 0;
    width: 120%;
    background: #0468ba;}

.third-nav>li:hover .fourth-nav {
    display:block;}