window.onload = function()
/* - this tells the browser to load the new table class from the CSS, namely ".hover" - */
{
  var table = document.getElementsByTagName("table");
  for(var t = 0; t < table.length; t++){
   table[t].onmouseover = function(){
    this.className += " hover";
   }
   table[t].onmouseout = function(){
    this.className = this.className.replace("hover", "");
   }
  }
/* - same as above, except this gets the class, of the same name, assigned to tr or table row  - */
{
  var tr = document.getElementsByTagName("tr");
  for(var r = 0; r < tr.length; r++){
   tr[r].onmouseover = function(){
    this.className += " hover";
   }
   tr[r].onmouseout = function(){
    this.className = this.className.replace("hover", "");
   }
  }
}
}