body {
    font-family: sans-serif;
    padding:20px;
}

.calculator-container {
    max-width:300px;
}

.input-group {
    margin-bottom:10px;
}

label {
    display:block;
    margin-bottom:5px;
}

input {
    padding:5px;
    width:100%;
}

button {
    margin-top:10px;
    padding:10px;
    width:100%;
    cursor:pointer;
}