Use of AJax Collapsible Panel Extender tool in Asp.Net with attaractive background and Collapse and Expand images

First of all add a referance for AjaxControlToolKit to your page :: <%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp" %> Add following css inside <head> tag :: <style type="text/css"> .pnlCSS{ font-weight: bold; cursor: pointer; border: solid 1px #c0c0c0; width:30%; border-radius:10px; background-color:white; } .pnlClick { font-weight: bold; cursor: pointer; border: solid 1px #c0c0c0; width:30%; border-radius:10px; background-color:Gray; } .Water { font-weight:lighter; font-style:italic; color:Gray; width:220px; border-round:5px; } </style> Add two panel inside your <body> tag and Attach AjaxControlToolKit control and drag and drop the CollapsiblePanelExtender like below:: <asp:Panel ID="pnlClick" runat="server" CssClass="pnlClick"> <div style="width:100%; h...