function switch_style ( css_title )
{
  var i, link_tag ;
  for (i = 0, link_tag = document.getElementsByTagName("link") ;
    i < link_tag.length ; i++ ) {
    if ((link_tag[i].rel.indexOf( "stylesheet" ) != -1) &&
      link_tag[i].title) {
      link_tag[i].disabled = true ;
      if (link_tag[i].title == css_title) {
        link_tag[i].disabled = false ;
      }
    }
  }
}

function style_setter()
{
   var blogstyles = new Array();
   blogstyles[0] = 'red';
   blogstyles[1] = 'blue';
   blogstyles[2] = 'yellow';

   var d = new Date();
   var index = Math.round(d.getTime()/1000/24/60/60) % blogstyles.length;
   switch_style(blogstyles[index]);
}

style_setter();