/* Reset */
.menu ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

/* Menu ngang */
.menu > ul > li {
    display: inline-block;
    position: relative; /* QUAN TRỌNG */
}

/* Link chính */
.menu ul li a {
    display: block;
    background-color: blue;
    color: white;
    text-decoration: none;
    padding: 10px 20px;
    border-right: 1px solid white;
}

/* Hover menu chính */
.menu ul li a:hover {
    background-color: oldlace;
    color: black;
}

/* ===== SUBMENU ===== */
.submenu {
    display: none; /* ẩn */
    position: absolute;
    top: 100%;
    left: 0;
    width: 200px;
}

/* Hiện submenu khi hover */
.menu ul li:hover .submenu {
    display: block;
}

/* Submenu item */
.submenu li {
    display: block;
}

/* Submenu link */
.submenu li a {
    border: none;
    border-bottom: 1px solid white;
}