function bkgrnd() {};   bg = new bkgrnd () ; n = 0
   
  bg[n++] = "a1"
  bg[n++] = "a2"
  bg[n++] = "a3"
  bg[n++] = "a4"
  bg[n++] = "a5"
  bg[n++] = "a6"
  bg[n++] = "a7"
  //Just keep adding

  rnd = Math.floor(Math.random() * n) ; 
  
  
  document.getElementById("phila_gov_top").classname = bg[rnd];