body {
    font-family: sans-serif;
    background-color: #121212;
    color: #ffffff;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}

.container {
    text-align: center;
}

.input-group {
    margin: 1em 0;
}

input {
    width: 5em;
    padding: 0.5em;
    border: 1px solid #333;
    border-radius: 5px;
    background-color: #333;
    color: #fff;
}

button {
    padding: 0.5em 1em;
    border: none;
    border-radius: 5px;
    background-color: #007bff;
    color: #fff;
    cursor: pointer;
}

#result {
    font-size: 2em;
    margin-top: 1em;
}