body {
 background:white url(pics/backginicio.jpg) top no-repeat;
  margin:0;
  padding:0;
  font-family:arial;
  font-size:20px;
}
  
#maincontainer {
  margin:auto;     
  height:600px;
  width:870px;
}

#maincontent{
  width:870px;
  position:center;
}

#header{
  height:109px;
  position: relative;
}

#mainmenu{
  height:39px;
  width:870px;
  position:absolute;
  bottom:0px;
  padding-left:0px;
}