#paymentForm {
        max-width: 400px;
        margin: 0 auto;
        padding: 20px;
        border: 1px solid #ccc;
        border-radius: 5px;
        box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    }

    #paymentForm input[type="textbox"] {
        width: 100%;
        padding: 10px;
        margin-bottom: 15px;
        border: 1px solid #ccc;
        border-radius: 5px;
    }

    #btn {
        display: block;
        width: 100%;
        padding: 10px;
        background-color: #D16b86;
        color: white;
        border: none;
        border-radius: 5px;
        cursor: pointer;
    }

    .error {
        color: red;
    }

    .popup {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background: rgba(0, 0, 0, 0.5);
        display: flex;
        justify-content: center;
        align-items: center;
    }

    .popup-content {
        background: white;
        padding: 20px;
        border-radius: 8px;
        box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
        text-align: center;
    }

    .popup button {
        background: #D16b86;
        color: white;
        border: none;
        padding: 8px 16px;
        border-radius: 4px;
        cursor: pointer;
    }