Add CSP directive

sites/+components/page-head.php

@@ -1,3 +1,10 @@
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <link rel="icon" type="image/svg+xml" href="favicon.svg" sizes="any">
+<meta 
+    http-equiv="Content-Security-Policy" 
+    content="
+        script-src 'self'; img-src 'self'; connect-src 'self'; font-src 'none';
+        object-src 'none'; media-src 'none'; form-action 'none'; base-uri 'self';
+    "
+>