// JavaScript Document
function winW() { 
if (window.innerWidth) return window.innerWidth; 
else if (document.documentElement && document.documentElement.clientWidth) 
return document.documentElement.clientWidth; 
else if (document.body && document.body.clientWidth) 
return document.body.clientWidth; 
else return null; 
} 
function winH() { 
if (window.innerHeight) return window.innerHeight; 
else if (document.documentElement && document.documentElement.clientHeight) 
return document.documentElement.clientHeight; 
else if (document.body && document.body.clientHeight) 
return document.body.clientHeight; 
else return null; 
} 

function posun(){ 
//zmena horizontální polohy 
var sirkaOkna = winW(); 
mujDiv = document.getElementById("ruka"); 
sirkaDivu = mujDiv.style.width; 
mujDiv.style.left = 0+"px"; 
//zmena vertikální polohy 
var vyskaOkna= winH(); 
vyskaDivu = mujDiv.style.height; 
mujDiv.style.top = (vyskaOkna/2-295)+"px"; 
}