.form-container {
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    width: 100%;
    max-width: 400px;
    box-sizing: border-box;
}

.form-step {
    display: none;
}

.form-step-active {
    display: block;
}

input, select {
    display: block;
    width: calc(100% - 20px);
    padding: 10px;
    margin-bottom: 10px;
    border: 1px solid #ccc;
    border-radius: 4px;
    box-sizing: border-box;
}

.calc-button {
    padding: 10px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    margin-top: 10px;
    width: 100%;
    box-sizing: border-box;
}

.result {
    margin-top: 20px;
    font-weight: bold;
    text-align: center;
}

.error-message {
    color: red;
    display: none;
    font-size: 12px;
    margin-top: -10px;
    margin-bottom: 10px;
}

input.invalid {
    border-color: red;
}