[FIX] Offline PWA functionality and style offline page

breccia_mapper/templates/offline.html

@@ -0,0 +1,8 @@
+{% extends 'base.html' %}
+
+{% block content %}
+<h2>Offline</h2>
+
+<p>You are currently offline. Please connect to a network to use this platform.</p>
+
+{% endblock %}