#rtc-calculator {
    max-width: 600px;
    background: #ffffff;
    padding: 20px;
    border: 1px solid #ccc;
    border-radius: 8px;
    margin: 20px auto;
    font-family: Arial, sans-serif;
    color: #000;
}
#rtc-calculator h2 { color: #000; }
#rtc-calculator label { display: block; margin-top: 10px; font-weight: bold; color: #000; }
#rtc-calculator input, #rtc-calculator select {
    width: 100%; padding: 8px; margin-top: 5px; margin-bottom: 10px;
    border: 1px solid #ccc; border-radius: 4px; color: #000; background: #fff;
}
#rtc-calculator button {
    padding: 10px 15px; margin-right: 10px;
    border: none; border-radius: 4px; cursor: pointer;
}
#rtc-add { background: #0073e6; color: #fff; }
#rtc-calc { background: #333; color: #fff; }
#rtc-add:hover { background: #005bb5; }
#rtc-calc:hover { background: #000; }

#rtc-results {
    margin-top: 20px; padding: 15px;
    background: #eaf3ff; border: 1px solid #cce;
    border-radius: 6px;
}
.rtc-pre-tax { color: green; font-weight: bold; }
.rtc-tax-amount { color: red; font-weight: bold; }