body {
    margin: 0;
    font-family: Arial, sans-serif;
}

#menu-huit, .sub-menu, .sub-menu-3 {
    list-style: none;
    padding: 0;
    margin: 0;
    background-color: blue;
}

/*  MENU CẤP 1  */
#menu-huit {
    display: flex;        
    width: 100%;          
}

#menu-huit > li {
    flex: 1;             
    border-right: 1px solid white;
    position: relative;
    text-align: center;
}

#menu-huit > li:last-child {
    border-right: none;
}

#menu-huit > li > a {
    display: block;
    padding: 15px 0;      
    color: white;
    text-decoration: none;
    font-weight: bold;
    font-size: 13px;
    white-space: nowrap; 
}

/*  MENU CẤP 2  */
.sub-menu {
    position: absolute;
    top: 100%;
    left: 0;
    width: 250px;       
    display: none;
    z-index: 100;
}

.sub-menu li {
    border-bottom: 1px solid white;
    text-align: left;
}

.sub-menu li a {
    display: block;
    padding: 12px 20px;
    color: white;
    text-decoration: none;
}

/*  MENU CẤP 3  */
.sub-menu-3 {
    position: absolute;
    top: 0;
    left: 100%;
    width: 220px;
    display: none;
}

/* HIỆU ỨNG HOVER  */
li:hover > ul {
    display: block;
}

#menu-huit li a:hover, .active {
    background-color: oldlace !important;
    color: blue !important;
}