.calculator {
    /* max-width: 420px; */
    margin: 40px auto;
    padding: 20px;
}

.calculator h1 {
    margin-bottom: 20px;
}

.calculator form {
    display: grid;
    gap: 16px;
}

.calculator input {
    width: 100%;
    padding: 10px;
    font-size: 16px;
}

.calculator button {
    padding: 12px;
    background: #0d1b2a; /* navy UPX */
    color: #fff;
    border: none;
    cursor: pointer;
}

.result {
    margin-top: 20px;
    padding: 14px;
    border-radius: 6px;
    font-weight: bold;
}

.hidden {
    display: none;
}