Turn TextBox.Text to CAPITAL or small letter in CSS

I'm looking for a simple function that turn the text of a TextBox into capital or small letter, but most of the JavaScript I found are clumsy because of the incompatibility of script (including the inconsistent behavior of event.keyCode and event.which in different browser).

Finally I found a pretty simple solution - CSS text-transform property do the work prettily. (http://www.w3.org/TR/CSS2/text.html#caps-prop)

E.g. [asp:TextBox ID="TextBox1" runat="server" style="text-transform:uppercase;" /]