igGrid - icon style changed

by georgianastasov

HTML

<script src="https://igniteui.com/js/modernizr.min.js"></script>
<script src="https://code.jquery.com/jquery-1.9.1.min.js"></script>
<script src="https://code.jquery.com/ui/1.10.3/jquery-ui.min.js"></script>
<script src="https://cdn-na.infragistics.com/igniteui/latest/js/infragistics.core.js"></script>
<script src="https://cdn-na.infragistics.com/igniteui/latest/js/infragistics.lob.js"></script>
<script src="https://igniteui.com/js/apiviewer.js"></script>
<script src="https://igniteui.com/js-data/northwind"></script>
<link href="https://cdn-na.infragistics.com/igniteui/latest/css/themes/infragistics/infragistics.theme.css" rel="stylesheet"></link>
<link href="https://cdn-na.infragistics.com/igniteui/latest/css/structure/infragistics.css" rel="stylesheet"></link>
<link href="https://igniteui.com/css/apiviewer.css" rel="stylesheet" type="text/css"></link>

<table id="grid" style="margin-bottom: 1rem;"></table>
<ul id="tree" style="margin-bottom: 1rem; background-color: black;"></ul>
<input type="button" id="changeColor" value="Change Color" />

CSS

/* setting the color of the columns according to your preference */
.ui-igcombo-buttonicon{
  color: white !important;
}

.ui-iggrid-addrowicon{
  color: white !important;
}

.ui-iggrid-colindicator{
  color: white !important;
}

.ui-igtree-expander{
  color: white !important;
}

.diffColor{
  color: yellow !important;
}

.ui-corner-all{
  
}

JavaScript

$(function () {

            var countries = ["UK", "USA"];

            /*----------------- Instantiation -------------------------*/
            $("#grid").igGrid({
                virtualization: false,
                autoGenerateColumns: false,
                renderCheckboxes: true,
                width: "100%",
                height: "400px",
                primaryKey: "EmployeeID",
                columns: [{
                    headerText: "Employee ID", key: "EmployeeID", dataType: "number"
                },
                {
                    headerText: "First Name", key: "FirstName", dataType: "string"
                },
                {
                    headerText: "Last Name", key: "LastName", dataType: "string"
                },
                {
                    headerText: "Country", key: "Country", dataType: "string"
                }
                ],
                dataSource: northwind,
                dataSourceType: "json",
                responseDataKey: "results",
                features: [
                		{
                        name: "Sorting",
                        type: "local"
                    },
                    {
                        name: "Responsive",
                        enableVerticalRendering: false,
                        columnSettings: [
                            {
                                columnKey: "EmployeeID",
                                classes: "ui-hidden-phone"
                            },
                            {
                                columnKey: "PostalCode",
                                classes: "ui-hidden-phone"
                            },
                            {
                                columnKey: "BirthDate",
                                classes: "ui-hidden-phone"
                            }
                        ]
                    },
                    {
                        name: "Selection",
                  ...