ListBox3.aspx font size:
<html>
<head>
<title>Adding Items to a List Control Programmatically</title>
<link rel="stylesheet" href="/shared/netdemos.css">

<style type="text/css">
<!--
   #msg {padding:10}
-->
</style>

<script language="C#" runat="server">
void applyColor ( object src, EventArgs e ) {
   msg.Style [ "background-color" ] = colorSelect.SelectedItem.Value;
}

void addToList ( object src, EventArgs e ) {
   colorSelect.Items.Add ( txtColor.Value );
}
</script>
</head>

<body>
<!-- #include virtual="~/shared/top.inc -->
<div class="header"><h2>Adding Items to a List Control Programmatically</h2></div>

<!-- #include virtual="~/shared/viewsrc_top.inc" -->
<hr size=1 width=92%>

<div align="center">
<form runat="server">

<p><span id="msg" runat="server">Click the button to apply a background color to this span.</span>


   <p>Select a color: <asp:ListBox id="colorSelect" runat="server">
      <asp:ListItem>SkyBlue</asp:ListItem>
      <asp:ListItem>LightGreen</asp:ListItem>
      <asp:ListItem>Gainsboro</asp:ListItem>
      <asp:ListItem>LemonChiffon</asp:ListItem>
   </asp:ListBox>

   <input type=button runat="server" Value="Apply" onServerClick="applyColor">

   <p>Don&rsquo;t see your color in the list above?  You can add it here:<br>

   <input type=text id="txtColor" runat="server">
   <input type=button runat="server" Value="Add to List" onServerClick="addToList">

</form>
</div>

<hr size=1 width=92%>
<!-- #include virtual="~/shared/viewsrc.inc" -->

</body>
</html>