.container {
    width: 80%;
    margin: 50px auto;
    font-family: Arial, sans-serif;
}

.group {
    background-color: #f3f4f6;
    border: 1px solid #ccc;
    margin-bottom: 20px;
    padding: 10px;
    border-radius: 8px;
}

.group:nth-child(odd) {
    background-color: #e6f7ff;
}

.group:nth-child(even) {
    background-color: #ffe6cc;
}

h1 {
    color: #333;
    text-align: center;
}