$a->page['htmlhead'] = str_replace('{{$stylesheet}}',$stylesheet,$a->page['htmlhead']);
//$a->page['htmlhead'] = replace_macros($a->page['htmlhead'], array('$stylesheet' => $stylesheet));
$a->page['htmlhead'] = str_replace('{{$stylesheet}}',$stylesheet,$a->page['htmlhead']);
//$a->page['htmlhead'] = replace_macros($a->page['htmlhead'], array('$stylesheet' => $stylesheet));