* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: Arial, sans-serif; padding: 20px; }

.main-menu {
    display: flex;
    background-color: blue;
    list-style: none;
}

.main-menu > li {
    position: relative; 
    border-right: 1px solid white;
}

.main-menu a {
    display: block;
    padding: 12px 15px;
    color: white;
    text-decoration: none;
    font-size: 13px;
    text-align: center;
}

.main-menu li:hover > a {
    background-color: oldlace;
    color: blue;
}

.sub-2, .sub-3 {
    list-style: none;
    position: absolute;
    background-color: blue;
    display: none; 
    min-width: 180px;
    z-index: 100;
}

.sub-2 {
    top: 100%; 
    left: 0;
}

.sub-2 li {
    border-top: 1px solid white;
    position: relative; 
}

.sub-2 a { text-align: left; }

.sub-3 {
    top: 0;
    left: 100%; 
}

.has-sub:hover > .sub-2,
.has-sub-right:hover > .sub-3 {
    display: block;
}