body {
    font-family: 'Arial', sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f5f5f5;
}

header {
    background-color: #3498db;
    color: #ffffff;
    text-align: center;
    padding: 1em 0;
}

h1 {
    margin: 0;
    font-size: 2em;
}

.calculator-section {
    max-width: 600px;
    margin: 20px auto;
    background-color: #ffffff;
    padding: 20px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    border-radius: 8px;
}

input, select {
    width: 100%;
    padding: 10px;
    margin: 10px 0;
    box-sizing: border-box;
    border: 1px solid #ccc;
    border-radius: 4px;
}

button {
    background-color: #3498db;
    color: #ffffff;
    padding: 10px 15px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
}

pre {
    background-color: #f8f8f8;
    padding: 10px;
    border-radius: 4px;
    overflow-x: auto;
}

/* Media query for responsiveness */
@media only screen and (max-width: 600px) {
    .calculator-section {
        max-width: 100%;
        margin: 10px;
        padding: 15px;
    }
}