3
if you are wanting a W3C valid template then adding
<link rel="stylesheet" type="text/css" href="<{$xoops_url}>/modules/yourmodule/yourstylesheet.css" />
will make the templates invalid.
you're better to use >
$xoTheme->addStylesheet(XOOPS_URL.'/modules//stylesheet.css');
place that code right after where it says
include XOOPS_ROOT_PATH . '/header.php';
in the php file itself. that will then inject the stylesheet into the of the theme during parsing.
including the link in the template itself will also not work fully if you have module cache enabled too. so the $xoTheme method is best..