var myImage

function fitToScreen () {
	myImage = document.getElementById("startBack");
	myContainer = document.getElementById("image-container");
	myContainer.style.width = Fensterweite()+"px";
	myContainer.style.height = Fensterhoehe()+"px";

	imgRatio = myImage.width/myImage.height;
	screenRatio = Fensterweite()/Fensterhoehe();
	
	if (imgRatio < screenRatio) {
		myImage.width = Fensterweite();	
		myImage.height = myImage.width/imgRatio;
	} else {
		myImage.height = Fensterhoehe();
		myImage.width = myImage.height*imgRatio;
	}
}