function getWindowHeight() {
			var windowHeight = 0;
			if (typeof(window.innerHeight) == 'number') {
				windowHeight = window.innerHeight;
			}
			else {
				if (document.documentElement && document.documentElement.clientHeight) {
					windowHeight = document.documentElement.clientHeight;
				}
				else {
					if (document.body && document.body.clientHeight) {
						windowHeight = document.body.clientHeight;
					}
				}
			}
		return windowHeight; 
}
		
function setBackground() {
	if (document.getElementById) {
		var windowHeight = getWindowHeight();
		if (windowHeight > 0) {
			var allHeight = document.getElementById('all').offsetHeight;
			var inhaltHeight = document.getElementById('content').offsetHeight;
			var navi2Height = document.getElementById('navi2').offsetHeight;
			var kopfHeight = document.getElementById('kopf').offsetHeight;
			var impressumElement = document.getElementById('impressum');
			var impressumHeight  = impressumElement.offsetHeight;

					
			if (windowHeight > (inhaltHeight + navi2Height + kopfHeight + impressumHeight)) {
				document.getElementById('all').style.height = windowHeight + 'px';
				impressumElement.style.position = 'absolute';
				impressumElement.style.top = (windowHeight - impressumHeight ) + 'px';

			} 
			if (windowHeight <= (inhaltHeight + navi2Height + kopfHeight + impressumHeight)) {
				document.getElementById('all').style.height = allHeight + 'px';
				impressumElement.style.position = 'absolute';
				impressumElement.style.top = (allHeight - impressumHeight ) + 'px';
			}
			
			
			
		}
	}
}