ASP.NET

  <br />
<table border="0" cellpadding="0" cellspacing="0" style="width:100%"><br />
            <tr><br />
                <td runat="server" id="tdMain"><br />
                       Put content here<br />
                </td><br />
             </tr><br />
   </table><br />
<br />
Server side code should be like this<br />
me.tdMain.Style.Add(" background-color", "red");<br />

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The idea is that you put all the content of your page inside the single table cell and it will affect the entire page.<br />
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<form id="Form1" runat="server"><br />
<table border="0" cellpadding="0" cellspacing="0" style="width:100%"><br />
<tr><br />
<td runat="server" id="tdMain"><br />
<br />
ALL CONTENT<br />
<br />
<br />
</td><br />
</tr><br />
</table><br />
</form><br />
<br />
<br />
You can modify the style of tdMain from any event. You can add and remove style elements during the button_click event.<br />

<script type="text/javascript"><br />
function ButtonPress (evt, btnID) {<br />
if (evt.keyCode == "13") <br />
{evt.returnValue= false ; evt.cancel= true ; document.getElementById(btnID).click(); return false; }<br />
}<br />
</script><br />
<br />
In the codebhind add the following.<br />
Dim ObjButton as Button = UserControl.Findcontrol("ButtonId")<br />
<br />
Me.Textbox1.Attributes.Add("onKeyPress", "ButtonPress(event, '" & ObjButton.ClientID & "')")<br />
          <br />
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Textbox txt = (Textbox) Usercontrol.FindControl("TextboxID");<br />
this.txt.Attributes.Add("onKeyPress", "ButtonPress(event, '" &<br />
this.Button.ClientID & "')");<br />