设置 treeview 选中节点的样式。

foreach (TreeNode node in this.tvs.Nodes)
                        {
                            TreeNode treeNode = FindNode(node, Request.QueryString["fenlei"].ToString());
                            if (treeNode != null)
                            {
                                treeNode.CollapseAll();
                                treeNode.Selected = true;                                treeNode.se
                                //TreeNode t1 = new TreeNode();
                                //t1.CssText = "FONT-SIZE: xx-small;COLOR: white;";
                                //t.Nodes.Add(t1);
                                //state = 1;
                                break;
                            }
 } private TreeNode FindNode(TreeNode tnParent, string strValue)
        {
            TreeNode treeNode2 = new TreeNode();
            string venueCode = "";
            if (tnParent == null) return null;
            if (tnParent.Value == strValue) return tnParent;
            tnParent.Expand();
            TreeNode tnRet = null;
            foreach (TreeNode tn in tnParent.ChildNodes)
            {
                //获得节点Value
                if (venueCode == "")
                {
                    //记录节点
                    treeNode2 = tn;
                    venueCode = tn.Value;
                }
                else
                {
                    //当选择节点发生变化时
                    if (venueCode != tn.Value)
                    {
                        treeNode2.Collapse();
                        venueCode = tn.Value;
                        treeNode2 = tn;
                    }
                }
                tnRet = FindNode(tn, strValue);
                if (tnRet != null) break;
            }
            return tnRet;
        }
这是刚开始选中默认节点。但是他的样式和其他的节点的样式是一样的。在这个代码的基础上怎么改变选中节点的样式。这样弄够区分和其他节点区分开来。