protected override void CreateChildControls()
{
_contentDiv = new HtmlGenericControl("div");
_contentDiv.Style[HtmlTextWriterStyle.Display] = "none";
var container = new HtmlGenericControl("div");
container.Attributes.Add("class", ContainerCSSClass);
_contentDiv.Controls.Add(container);
for(var i = 0; i < Content.Count; i++)
container.Controls.Add(Content[i]);
Controls.Add(_contentDiv);
base.CreateChildControls();
}