body {
    font-family: Arial;
    background: #f2f2f2;
    margin: 0;
}

.container {
    max-width: 520px;
    margin: auto;
    padding: 20px;
}

h1 {
    text-align: center;
}

.grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
}

.card {
    background: white;
    padding: 18px;
    border-radius: 15px;
    text-align: center;
    cursor: pointer;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
}

.card.selected {
    background: #0077ff;
    color: white;
}

button {
    width: 100%;
    padding: 18px;
    font-size: 20px;
    background: green;
    color: white;
    border: none;
    border-radius: 12px;
    margin-top: 20px;
}

.result {
    background: white;
    margin-top: 15px;
    padding: 15px;
    border-radius: 12px;
}