Thank you very much. I've added the following to my _layout.cshtml:
<link id="theme" rel='nofollow' href="_content/Syncfusion.Blazor.Themes/bootstrap5.css" rel="stylesheet" />
<script src="_content/Syncfusion.Blazor.Core/scripts/syncfusion-blazor.min.js" type="text/javascript"></script>
It is now working fine. I appreciate the fast responses that the Syncfusion team are providing in this forum. Excellent work everyone!!!
Mike