function check_width() {
 if(screen.width <= 800) {
  document.getElementById('img_head').src = 'images/head_750.jpg';
  document.getElementById('img_head').width = 750;
  document.getElementById('img_head').height = 115;
 } else {
  document.getElementById('img_head').src = 'images/head_2.jpg';
  document.getElementById('img_head').width = 973;
  document.getElementById('img_head').height = 150;
 }
}


function image_change(arr_id, id, id2, image) {

	document.getElementById(id).src = image;
	
	for(var i = 0; i < arr_id.length; i++)
	if(arr_id[i] == id2) {
		document.getElementById(id2).className = 'gallery_activ';
  } else {
    document.getElementById(arr_id[i]).className = 'gallery_normal';
  }
	
}

if(screen.width <= 800) {
 document.getElementById('css_tag').href = '_style_750.css';
}