function setColor(el, bg) 
{
    if (el.style) el.style.backgroundColor = bg;
}

function checkInput(form) 
{
	var bgBad = "#68CBF0";
	var bgGood = "#FFFFFF";
	var valid = true;
	
	if (form.username.value == "") 
	{
	    valid = false;
	    setColor(form.username, bgBad);
	} 
	else
	{
	    setColor(form.username, bgGood);
	}

	if (form.password.value == "") 
	{
	    valid = false;
	    setColor(form.password, bgBad);
	} 
	else
	{
	    setColor(form.password, bgGood);
	}
		
	return valid;
}