cls

An optional CSS class to apply to the main rendering element of the MaskedTextBox.
The properties in this class will override any control and theme-specific properties.

<input id="maskedtextbox" />

<style>
    .pink { background-color:pink; }
</style>

<script type="text/javascript">
    $(function () {
        $("#maskedtextbox").shieldMaskedTextBox({
            mask: "000,000.00$",
            cls: "pink"
       });
    });
</script>