<telerik:RadScheduler RenderMode="Lightweight" runat="server" ID="RadScheduler1" OnPreRender="RadScheduler1_PreRender"
    Height="600px" SelectedDate="2012-04-16" Font-Size="14px" AccessKey="F" TabIndex="1" SelectedView="TimelineView" GroupBy="User" GroupingDirection="Vertical" RowHeight="50px"
    DayStartTime="08:00:00" DayEndTime="23:00:00" OverflowBehavior="Auto">
    <AdvancedForm Modal="true" />
</telerik:RadScheduler>
<%-- https://css-tricks.com/position-sticky-and-table-headers/ --%>
<style>
    div.RadScheduler .rsContentTable {
        overflow: visible
    }

    .rsContentScrollArea table {
        position: relative;
    }

    .sticky td, .sticky th {
        position: sticky;
        opacity: 1;
        z-index: 100;
        background: #e6e6e6;
        top: 0; /* Don't forget this, required for the stickiness */
    }
</style>

<script>

    function pageLoadHandler() {
        // improve logic to set the class to the desired rows, not the first one
        $telerik.$(".RadScheduler .rsAllDayTable tr").eq(0).addClass("sticky");
        $telerik.$(".RadScheduler .rsVerticalHeaderTable tr").eq(0).addClass("sticky");
    }
    Sys.Application.add_load(pageLoadHandler);
</script>