added different stylesheet

mymodule/themes/fancytheme/default/base.twig

@@ -5,7 +5,7 @@
     <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
     <meta name="viewport" content="initial-scale=1.0">
     <title>{{ pagetitle }}</title>
-    <link rel="stylesheet" href="{{ asset("/mymodule/stylesheet.css") }}">
+    <link rel="stylesheet" href="{{baseurlpath}}module.php/mymodule/stylesheet.css">
     <link rel="stylesheet" href="/css/bootstrap.min.css">
     <link rel="stylesheet" href="/css/m4lab.css">
     <link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.8.2/css/all.css" integrity="sha384-oS3vJWv+0UjzBfQzYUhtDYW+Pj2yciDJxpsK1OYPAYjqT085Qq/1cq5FLXAZQ7Ay" crossorigin="anonymous">