How to set autocomplete selected item with gray background?

Question

I work on asp.net mvc call api using ajax jquery . I face issue on design auto complete

My issue auto complete selected item not display with gray background

I don't know how to do that

my code details

 $(document).ready(function () {
  
        $("#txtLineManagerId").autocomplete({
            source: function (request, response) {
                var searchText = $("#txtLineManagerId").val();
                console.log("search text" + searchText)
                $.ajax({
                    url: '@Url.Action("GetAllEmployeeBasedSearchText", "Resignation")',
                    data: { searchText: searchText },
                    method: "GET",
                    dataType: "json",
                    success: function (data) {
                        response($.map(data, function (item) {
                         
                            return { label: item.EmployeeID + " - " + item.EmployeeName + " - " + item.Designation , value: item.EmployeeID, employeeName: item.EmployeeName };

                        }))

                    }
                });
            },
            position: { my: "right top", at: "right bottom" },
            appendTo: '#searchContainer',
            select: function (event, ui) { 
                $("#LineManagerName").val(ui.item.employeeName);
    
            },
            minLength: 4,
        
        });

         <div class="col-md-7">
                    @Html.EditorFor(model => model.LineManager, new { htmlAttributes = new { @class = "form-control", id = "txtLineManagerId" } })
                    <div id="searchContainer">

                    </div>
                 
                </div>
 <div class="col-md-7">

                  
  </div>

sample for expected result I need

selection with gray color expected