Initial user management.

templates/404.html

@@ -0,0 +1,9 @@
+{% extends "layout.html" %}
+
+{% block content %}
+<div class="error-container">
+    <h1>404 - Page Not Found</h1>
+    <p>The page you are looking for does not exist.</p>
+    <a href="{{ url_for('home') }}" class="btn">Return to Home</a>
+</div>
+{% endblock %}