function changeBack(page) {
	if (page =='0') {
		document.getElementById('content_img').style.backgroundImage = 'url(/img/mediation.jpg)';
	}
	
	else if (page =='1') {
		document.getElementById('content_img').style.backgroundImage = 'url(/img/coaching.jpg)';
	}
	
	else if (page =='2') {
		document.getElementById('content_img').style.backgroundImage = 'url(/img/training.jpg)';
	}
	
	else if (page =='3') {
		document.getElementById('content_img').style.backgroundImage = 'url(/img/bedrijfsbegeleiding.jpg)';
	}
}