body {
    font-family: 'Arial', sans-serif;
    background-color: #f4f4f9;
    margin: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
}

header {
    background-color: #24292e;
    color: white;
    width: 100%;
    padding: 2rem 0;
    text-align: center;
}

.card {
    background: white;
    padding: 2rem;
    margin-top: 2rem;
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    max-width: 400px;
    text-align: center;
}

button {
    background-color: #28a745;
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 5px;
    cursor: pointer;
}

button:hover {
    background-color: #218838;
}