.gst-calculator-box {
    max-width: 420px;
    background: #ffffff;
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.1);
    font-family: Arial, sans-serif;
}

.gst-calculator-box h2 {
    text-align: center;
    margin-bottom: 15px;
}

.gst-calculator-box label {
    display: block;
    margin-top: 10px;
    font-weight: bold;
}

.gst-calculator-box input,
.gst-calculator-box select {
    width: 100%;
    padding: 10px;
    margin-top: 5px;
    border-radius: 5px;
    border: 1px solid #ccc;
}

.gst-calculator-box button {
    width: 100%;
    margin-top: 15px;
    padding: 12px;
    background: #0073aa;
    color: #fff;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 16px;
}

.gst-calculator-box button:hover {
    background: #005177;
}

.result-box {
    margin-top: 15px;
    background: #f1f7ff;
    padding: 10px;
    border-radius: 6px;
}

.error {
    color: red;
    font-weight: bold;
}