body {
    margin: 0;
    padding: 0;
    font-family: Arial, sans-serif;
    background: url('https://example.com/your-background-image.jpg') no-repeat center center fixed;
    background-size: cover;
    color: #fff;
}

.container {
    max-width: 600px;
    margin: 0 auto;
    padding: 20px;
    background-color: rgba(0, 0, 0, 0.8); /* Darker, more opaque background for better contrast */
    border-radius: 15px;
    text-align: center;
}

header h1 {
    margin: 0;
    font-size: 2.5em;
    color: #fff;
}

main {
    margin-top: 30px;
}

.button-container {
    display: flex;
    flex-direction: column; /* Stack buttons vertically */
    gap: 15px;
}

.calc-button {
    background: linear-gradient(135deg, #28a745, #218838);
    border: none;
    border-radius: 10px;
    color: #fff;
    padding: 15px 20px;
    font-size: 1.2em;
    cursor: pointer;
    transition: all 0.3s ease;
    text-transform: uppercase;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.2);
}

.calc-button:hover {
    background: linear-gradient(135deg, #218838, #28a745);
    transform: translateY(-3px);
    box-shadow: 0 6px 8px rgba(0, 0, 0, 0.3);
}

footer {
    margin-top: 20px;
    font-size: 0.9em;
    color: #ccc;
}