function showBigImage(image) {
  var width = document.all ? document.body.clientWidth : window.innerWidth;
  var height = document.all ? document.body.clientHeight : window.innerHeight;
  var scrollOffset = document.all ? document.body.scrollTop : window.pageYOffset;

  document.getElementById('darken').style.width = width;
  document.getElementById('darken').style.height = height;
  document.getElementById('darken').style.top = scrollOffset;
  document.getElementById('darken').style.display = 'block';
  document.getElementById('bigImage'+image).style.top = (height/2) + scrollOffset;
  document.getElementById('bigImage'+image).style.display = 'block';
}
function hideBigImage(image) {
  document.getElementById('darken').style.display = 'none';
  document.getElementById('bigImage'+image).style.display = 'none';
}