Polish typography and responsive admin navigation

app/templates/_user_menu.html

@@ -4,6 +4,7 @@
         <a href="/profile">Mein Profil</a>
         <a href="/messages">Nachrichten{% if user.unread_message_count %} <span class="menu-count">{{ user.unread_message_count }}</span>{% endif %}</a>
         {% if user.event_invitation_count %}<a href="/#event-invitations">Veranstaltungseinladungen <span class="menu-count">{{ user.event_invitation_count }}</span></a>{% endif %}
+        {% if user.is_admin %}<a href="/admin">⚙️ Verwaltung</a>{% endif %}
         <form method="post" action="/logout">
             <button type="submit">Abmelden</button>
         </form>

app/templates/concert_detail.html

@@ -14,7 +14,7 @@
 
     <link
         rel="stylesheet"
-        href="/static/style.css"
+        href="/static/css/style.css"
     >
 
     <style>

app/templates/index.html

@@ -175,7 +175,7 @@
         }
 
         .page-header { padding: 24px; border: 1px solid #5f1515; border-left: 4px solid #dc2626; border-radius: 14px; background: linear-gradient(110deg, rgba(10,10,10,.9), rgba(69,10,10,.28)); box-shadow: 0 12px 30px rgba(0,0,0,.3); }
-        .page-header h1 { font-family: Impact, Haettenschweiler, "Arial Narrow Bold", sans-serif; letter-spacing: .05em; text-transform: uppercase; text-shadow: 0 2px 18px rgba(185, 28, 28, .45); }
+        .page-header h1 { font-family: "Metal Mania", Impact, Haettenschweiler, "Arial Narrow Bold", sans-serif; letter-spacing: .05em; text-transform: uppercase; text-shadow: 0 2px 18px rgba(185, 28, 28, .45); }
         .new-concert-button { background: #991b1b; border: 1px solid #dc2626; }
         .new-concert-button:hover { background: #b91c1c; }
         .admin-button:hover { border-color: #dc2626; }
@@ -248,14 +248,6 @@
                 {% if archive %}⚡ Bevorstehend{% else %}☠ Vergangene{% endif %}
             </a>
 
-            {% if user.is_admin %}
-
-                <a href="/admin" class="admin-button">
-                    ⚙️ Verwaltung
-                </a>
-
-            {% endif %}
-
             <a
                 href="/concerts/new"
                 class="new-concert-button"