offY = 30;
posY = offY;
function floatMenu()
{
var boxbanaObj = document.getElementById("boxbana");

if(!( boxbanaObj == null || boxbanaObj == undefined )){
sy = document.body.scrollTop;
  boxbanaObj.style.top = posY;
  movY = sy-posY+offY;
  cY = movY/2;
  posY += cY;
}
}