<script language="javascript">
function get_color(){
	if(document.getElementById('input3').value!="00"){
		document.getElementById('input3').style.color='#006600';
	}
}
</script>
<input type="text" name="input3" value="00" style="color:#FF0000;" readonly="readonly">
<input type="button" value="ok" onclick="document.getElementById('input3').value='01'; get_color();" />