/* ========== RESET ========== */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

/* ========== BODY ========== */
body {
    font-family: Arial, sans-serif;
    background: linear-gradient(to right, #dbeafe, #eff6ff);
    min-height: 100vh;
}

/* =================================
   MENU NGANG (BÀI 1)
================================= */
.menu-top {
    margin-top: 30px;
    display: flex;
    justify-content: center;
}

.menu-top ul {
    list-style: none;
    display: flex;
    background: blue;
}

.menu-top li {
    list-style: none;
    position: relative;
    border-right: 1px solid white;
}

.menu-top li:last-child {
    border-right: none;
}

.menu-top a {
    display: block;
    padding: 15px 30px;
    color: white;
    text-decoration: none;
}

.menu-top a:hover {
    background: oldlace;
    color: black;
}

/* submenu ngang */
.menu-top .submenu {
    position: absolute;
    top: 100%;
    left: 0;
    display: none;
    min-width: 180px;
}

.menu-top li:hover > .submenu {
    display: block;
}

.menu-top .submenu a {
    background: blue;
    padding: 12px;
}

/* =================================
   MENU DỌC (BÀI 2)
================================= */
#menu-side {
    width: 200px;
    margin: 50px;
}

#menu-side li {
     list-style: none;
    position: relative;
}

#menu-side a {
    display: block;
    padding: 12px 15px;
    background: #000;
    color: #fff;
    text-decoration: none;
    border-bottom: 1px solid #fff;
}

#menu-side a:hover {
    background: darkgray;
    color: #000;
}

/* submenu dọc */
#menu-side .submenu {
    position: absolute;
    top: 0;
    left: 100%;
    display: none;
    min-width: 180px;
    background: #000;
}

#menu-side li:hover > .submenu {
    display: block;
}

/* =================================
   TRANG CHỦ
================================= */
.home-container {
    width: 90%;
    max-width: 1000px;
    margin: 100px auto;
    text-align: center;
    background: white;
    padding: 50px;
    border-radius: 20px;
}

.task-list {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 25px;
}

.task-card {
    display: block;
    text-decoration: none;
    background: #2563eb;
    color: white;
    padding: 30px;
    border-radius: 18px;
}

.task-card:hover {
    background: #1d4ed8;
}

/* ========== RESPONSIVE ========== */
@media (max-width: 768px) {
    .task-list {
        grid-template-columns: 1fr;
    }
}

/* ===== MENU CẤP 2 (BÀI 3) ===== */
.menu-top .submenu .submenu {
    position: absolute;
    top: 0;
    left: 100%;
    display: none;
    background: blue;
    min-width: 180px;
}

/* Hiện cấp 2 */
.menu-top .submenu li:hover > .submenu {
    display: block;
}