I have a form that when I enter characters by keypress all other browsers it allows the user to do so. But when I use Firefox it doesn't allow the user to enter characters by key press but allows the user to copy and paste. Here is my script below:

```
<script language="javascript">
function aaa(){
            document.getElementById('txtwebref').style.color = 'black';
}
</script>

<input name="txtwebref" type="text" id="txtwebref" size="50" value="Insert reference number" style="width:350px; height:50px; border:1px solid #000; border-radius:15px; text-align:center;color:#CCC; font-family:Arial, Helvetica, sans-serif; font-size:24px;" onkeypress="if ( isNaN(this.value + String.fromCharCode(event.keyCode) )) return false;" onfocus="blank(this);" onblur="unblank(this)" onclick="aaa();"/>

```