Using the ASPX engine you can modify for instance the body class of the master page from an aspx template page in the following way:
protected override void OnInit(EventArgs e)
{
BodyClass = "home " + BodyClass;
base.OnInit(e);
}
Above I've added home class to the body tag. The space after the class name is used to separate it from the other BodyClass class names.
This works fine but I'd like a
confirmation from Kentico though that this is a good way to change the body class of the master page from an aspx page.