function checkNaamnb() {
	veld = document.getElementById("nb-naam");
	if(veld.value == "Uw naam") {
		veld.value = '';
	} else if(veld.value == 'Uw naam' || veld.value == '') {
		veld.value = 'Uw naam';
	}
}

function checkEmailnb() {
	veld = document.getElementById("nb-email");
	if(veld.value == "Uw e-mailadres") {
		veld.value = '';
	} else if(veld.value == 'Uw e-mailadres' || veld.value == '') {
		veld.value = 'Uw e-mailadres';
	}
}