fix: resolve broken lib/ require paths in admin and normalise modern-normalize to .min.css

templates/head.php

@@ -7,7 +7,7 @@
     <meta name="author" content="">
     <meta name="description" content="">
     <title><?= isset($pageTitle) ? htmlspecialchars($pageTitle) . ' - Posterg' : 'Posterg' ?></title>
-    <link rel="stylesheet" href="assets/modern-normalize.css">
+    <link rel="stylesheet" href="assets/modern-normalize.min.css">
     <link rel="stylesheet" href="assets/common.css">
     <?php if (isset($additionalCSS)): ?>
         <?php foreach ((array)$additionalCSS as $css): ?>