var direction=1;
var bgPos  = 0;

function Scroller(){
     bgPos == 2000? bgPos = 0 : bgPos = bgPos + direction;
     document.getElementById('clouds').style.backgroundPosition  =  bgPos + " 70";
     setTimeout("Scroller()",40);
}



function changecolor(o, color)
{
  if ( o )
  {
    o.style.backgroundColor = color;
  }
}



function menu(o)
{
  repos='#3080D0';
  actif='#40b0E0';

  changecolor(document.getElementById('M1'), repos);
  changecolor(document.getElementById('M2'), repos);
  changecolor(document.getElementById('M3'), repos);
  changecolor(document.getElementById('M4'), repos);
  changecolor(document.getElementById('M5'), repos);
  changecolor(document.getElementById('M6'), repos);
  changecolor(o, actif);
  direction == 1 ? direction = -1 : direction = 1;
}