function changeTabClass(id1, id2, id3, id4)
                   {
                       var div1 = document.getElementById(id1);            
                       var div2 = document.getElementById(id2);
                       var div3 = document.getElementById(id3);
                       var div4 = document.getElementById(id4);
                       div1.className = 'active';
                       div2.className = '';
                       div3.style.display = 'block';
                       div4.style.display = 'none';
                    }

                   function changeTabClassActive(id1, id2)
                   {
                       
                       var activeDiv1 = document.getElementById(id1);            
                       var activeDiv2 = document.getElementById(id2);
                      
                       var infoTab = document.getElementById('product_tabs_description');
                       var newsTab = document.getElementById('product_tabs_news');
                       var reviewsTab = document.getElementById('product_tabs_reviews');
                       var productsTab = document.getElementById('product_tabs_upsell_products');
                       var previewTab = document.getElementById('product_tabs_preview');
                       
                       var infoContent = document.getElementById('product_tabs_description_contents');
                       var newsContent = document.getElementById('product_tabs_news_contents');
                       var reviewsContent = document.getElementById('product_tabs_reviews_contents');
                       var productsContent = document.getElementById('product_tabs_upsell_products_contents');
                       var previewContent = document.getElementById('product_tabs_preview_contents');
                        

                       if (id1 == 'product_tabs_reviews')
                       { 
                              activeDiv1.className = 'active';
                              activeDiv2.style.display='block';
 
                              if(infoTab){infoTab.className = '';}
                              if(newsTab){newsTab.className = '';}
                              if(productsTab){productsTab.className = '';}
                              if(previewTab){previewTab.className = '';}

                              if(infoContent){infoContent.style.display = 'none';}
                              if(newsContent){newsContent.style.display = 'none';}
                              if(productsTab){productsContent.style.display = 'none';}
                              if(previewTab){previewContent.style.display = 'none';}
                       } 
                       else if (id1 == 'product_tabs_description')
                       {
                              activeDiv1.className = 'active';
                              activeDiv2.style.display='block';
 
                              if(reviewsTab){reviewsTab.className = '';}
                              if(newsTab){newsTab.className = '';}
                              if(productsTab){productsTab.className = '';}
                              if(previewTab){previewTab.className = '';}

                              if(reviewsContent){reviewsContent.style.display = 'none';}
                              if(newsContent){newsContent.style.display = 'none';}
                              if(productsContent){productsContent.style.display = 'none';}
                              if(previewContent){previewContent.style.display = 'none';}
                       }
                      else if (id1 == 'product_tabs_preview')
                      {
                             
                              activeDiv1.className = 'active';
                              activeDiv2.style.display='block';
 
                              if(infoTab){infoTab.className = '';}
                              if(newsTab){newsTab.className = '';}
                              if(productsTab){productsTab.className = '';}
                              if(reviewsTab){reviewsTab.className = '';}

                              if(infoContent){infoContent.style.display = 'none';}
                              if(newsContent){newsContent.style.display = 'none';}
                              if(productsContent){productsContent.style.display = 'none';}
                              if(reviewsContent){reviewsContent.style.display = 'none';}
                        }
                       else if (id1 == 'product_tabs_news')
                       {
                              activeDiv1.className = 'active';
                              activeDiv2.style.display='block';
 
                              if(infoTab){infoTab.className = '';}
                              if(previewTab){previewTab.className = '';}
                              if(productsTab){productsTab.className = '';}
                              if(reviewsTab){reviewsTab.className = '';}

                              if(infoContent){infoContent.style.display = 'none';}
                              if(previewContent){previewContent.style.display = 'none';}
                              if(productsContent){productsContent.style.display = 'none';}
                              if(reviewsContent){reviewsContent.style.display = 'none';}
                        }
                     else if (id1 == 'product_tabs_upsell_products')
                       {
                              activeDiv1.className = 'active';
                              activeDiv2.style.display='block';
 
                              if(infoTab){infoTab.className = '';}
                              if(previewTab){previewTab.className = '';}
                              if(newsTab){newsTab.className = '';}
                              if(reviewsTab){reviewsTab.className = '';}

                              if(infoContent){infoContent.style.display = 'none';}
                              if(previewContent){previewContent.style.display = 'none';}
                              if(newsContent){newsContent.style.display = 'none';}
                              if(reviewsContent){reviewsContent.style.display = 'none';}
                        }
                      else {}
                    }