body {
    font-family: Arial, sans-serif;
    background-color: #f4f4f4;
    margin: 0;
    padding: 20px;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    background-color: #fff;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    padding: 20px;
}

header {
    text-align: center;
    margin-bottom: 20px;
}

h1 {
    color: #333;
    font-size: 2em;
}

h2 {
    color: #555;
    font-size: 1.5em;
}

.tiles {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 20px;
}

.subject-tile {
    background-color: #f0f0f0;
    padding: 20px;
    border-radius: 5px;
    text-align: center;
}

.subject-tile h3 {
    color: #333;
    margin-bottom: 10px;
}

.dropdown {
    position: relative;
    display: inline-block;
}

.dropbtn {
    background-color: #4CAF50;
    color: white;
    padding: 10px;
    font-size: 16px;
    border: none;
    cursor: pointer;
    border-radius: 5px;
}

.dropdown-content {
    display: none;
    position: absolute;
    background-color: #f9f9f9;
    min-width: 160px;
    box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
    z-index: 1;
}

.dropdown-content a {
    color: black;
    padding: 12px 16px;
    text-decoration: none;
    display: block;
}

.dropdown-content a:hover {background-color: #f1f1f1}

.dropdown:hover .dropdown-content {
    display: block;
}

.dropdown:hover .dropbtn {
    background-color: #3e8e41;
}