body {
    margin: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
}

header {
    background-color: #333;
    color: white;
    padding: 15px 10px;
    text-align: center;
    width: 100%;
}
header h1 a {
    color: inherit;
    text-decoration: none;
}
main {
    flex: 1 0 auto;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    padding: 40px 20px;
}
.button-link {
    display: inline-block;
    padding: 16px 32px;
    background-color: #007bff;
    color: white;
    text-decoration: none;
    border-radius: 8px;
    font-weight: bold;
    font-size: 1.2rem;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    transition: background-color 0.3s ease, transform 0.2s ease;
    margin-top: 10px;
}

.button-link:hover {
    background-color: #0056b3;
    transform: translateY(-2px);
}
footer {
    background-color: #333;
    color: white;
    text-align: center;
    padding: 10px;
    width: 100%;
    flex-shrink: 0;
}

@media screen and (max-width: 600px) {
    header h1 {
        font-size: 1.5rem;
    }

    .calculator-container h2 {
        font-size: 1.5rem;
    }

    main {
        padding: 20px 10px;
    }

    .calculator-container {
        gap: 15px;
    }
}