// JavaScript Document
function changePreview(tabNumber) {
      var tabNames = ['slabs','countertop','statue','column','border','mosaic','fireplace','praver','machine'];
      
      for (i = 1; i <= tabNames.length; i++) {
        document.getElementById('detail' + i).style.display = 'none';
      }
      document.getElementById('detail' + tabNumber).style.display = '';

      lis = document.getElementById('top-nav').getElementsByTagName('li');
      for(i = 0; i < lis.length; i++) {
        if (lis[i].className == 'active menu')
          lis[i].className = 'menu';
      }
      document.getElementById('tab' + tabNumber).className = 'active menu';
     
    }