Change color of DateTime picker slider using CSS in ASP.Net

            $('#txtUntil').datetimepicker({
                stepMinute: 5,
                timeFormat: datetimePickerTimeFormat,
                dateFormat: datetimePickerDateFormat,
                numberOfMonths: 1,
                minDate: 0,
                prevText: translatedPrevText,
                nextText: translatedNextText,
                timeOnlyTitle: translatedTimeOnlyTitle,
                timeText: translatedTimeText,
                hourText: translatedHourText,
                minuteText: translatedMinuteText,
                secondText: translatedSecondText,
                currentText: translatedCurrentText,
                closeText: translatedCloseText,
                monthNames: translatedMonthNames,
                monthNamesShort: translatedMonthNamesShort,
                firstDay: 1,
                dayNames: translatedDayNames,
                dayNamesShort: translatedDayNamesShort,
                dayNamesMin: translatedDayNamesMin,
                showSecond: false,
                onClose: function (dateText, inst) {

                    var startDate = new Date($('#txtFrom').datepicker("getDate"));
                    var endDate = new Date($('#txtUntil').datepicker("getDate"));
                    var datediff = 0;
                    var now = new Date();

                    if ($("#txtFrom").val() == 'Now') {
                        startDate.setMinutes(now.getMinutes());
                        startDate.setHours(now.getHours());
                    }

                    if (endDate > startDate) {
                        datediff = endDate - startDate;
                    }

                    $("#hiddenDurationVal").val(datediff);
                }
            });
        });
<td>
  <asp:TextBox ID="txtUntil" runat="server" AutoPostBack="False" CssClass="EPinput" Width="185px"></asp:TextBox>
                                </td>