function hideImages() {
	document.getElementById("img1").className = 'hidden';
	document.getElementById("img2").className = 'hidden';
	document.getElementById("img3").className = 'hidden';
}
function showImg1() {
hideImages();
document.getElementById("img1").className = 'shown';
}

function showImg2() {
hideImages();
document.getElementById("img2").className = 'shown';
}
function showImg3() {
hideImages();
document.getElementById("img3").className = 'shown';
}