function hideElement(id) {
  document.getElementById(id).style.display = 'none';
}

function showAdvertisement(image, width, height) {
  var divAd = document.getElementById('global_advertisement');
  divAd.innerHTML = '<img src="images/advertisement/' + image + '" alt="Reklama" />';
  
  height += 40;
  width += 40;
  
  adContent = document.getElementById('ad_content');
  adContent.style.height = height + 'px';
  adContent.style.width = width + 'px';
  
  var marginLeft = Math.floor((width / 2)) + 1;
  adContent.style.marginLeft = '-' + marginLeft + 'px';
  
  var marginTop = Math.floor((height / 2)) + 1;
  adContent.style.marginTop = '-' + marginTop + 'px';

  document.getElementById('ad_fade').style.display = 'block';
  document.getElementById('ad_content').style.display = 'block';
}

function closeAdvertisement() {
  document.getElementById('ad_content').style.display = 'none';
  document.getElementById('ad_fade').style.display = 'none';
}