Hello,

All looks fine. I’ve did the following:

Declare the css class in the page like this:

 <style type="text/css">
    .styleCell
    {
        background-color : Red !important;    
    } 
    </style>

Important rule is needed in order to override the Item tbody.igg_Item > tr > td calss background property :

The grid is defined like this:

<ig:WebHierarchicalDataGrid ID="WebHierarchicalDataGrid1" Width="100%" 
         runat="server" Height="350px">
            <ClientEvents Initialize="gridInit"  RowExpanded="rowExpanded"/>
            <Behaviors>
                <ig:Selection CellSelectType="Multiple">
                    <AutoPostBackFlags CellSelectionChanged="True" />
                </ig:Selection>
                <ig:Activation>
                </ig:Activation>
            </Behaviors>
        </ig:WebHierarchicalDataGrid>

Code behind that I’m setting the css class is as follows:

 protected void Page_Load(object sender, EventArgs e)
    {
        WebHierarchicalDataGrid1.InitializeRow +=
            new Infragistics.Web.UI.GridControls

                 .InitializeRowEventHandler(WebHierarchicalDataGrid1_InitializeRow)

    }

    void WebHierarchicalDataGrid1_InitializeRow(object sender, Infragistics.Web.UI.GridControls.RowEventArgs e)
    {
            e.Row.Items[0].CssClass = "styleCell";
 
    }

The result is on the screenshot below:

From the link then I dont see what it is I'm doing wrong.

 Column @ Index 1

InitRow Code:

        protected void Report_Grid_InitializeRow(object sender, Infragistics.Web.UI.GridControls.RowEventArgs e)
        {
  e.Row.CssClass = "summaryRow";
                e.Row.Items[1].CssClass = "summaryCell";
        }

 Rendered Table Output: