text: var cur_img = 2;
  var cur_back = 1;
  var cur_trans = 1;
  
  
   var timerId1 = setInterval(function() {
  	if (cur_img == 2)
  	{
  		document.getElementById('polek').className = 'img1'; 
  		cur_img = 1;
  	}
  	else {
  		document.getElementById('polek').className = 'img2'; 
  		cur_img = 2;
  	}
  }, 1001);
  
  
  
   var timerId3 = setInterval(function() {
  	if (cur_back == 2)
  	{
  		document.body.style= 'background-image: url(images/back_1.png); transition: all 1.5s linear;'; 
  		cur_back = 1;
  	}
  	else {
  		document.body.style= 'background-image: url(images/back_2.png); transition: all 1.5s linear;';  
  		cur_back = 2;
  	}
  }, 2000);
  