sheets = document.styleSheets;
  elm.innerHTML = "sheets count:" + sheets.length + "<br>";
  
  for(i= 0 ;i<sheets.length;i++)
  {
    elm.innerHTML += "sheet info<br>";
    elm.innerHTML += "sheet " + i + " has " + sheets[i].rules.length + " rules<br>";
    for(j= 0 ;j<sheets[i].rules.length;j++)
    {
      elm.innerHTML += "rule " + j + " is " + sheets[i].rules.item(j).selectorText + "<br>";
      sheets[i].rules.item(j).style.backgroundColor = "yellow";
    }    
  }