diff --git a/ram/portal/templates/books.html b/ram/portal/templates/books.html
index 8b332a9..63998a8 100644
--- a/ram/portal/templates/books.html
+++ b/ram/portal/templates/books.html
@@ -46,11 +46,11 @@
                 </tr>
                 <tr>
                   <th scope="row">Pages</th>
-                  <td>{{ d.number_of_pages }}</td>
+                  <td>{{ d.number_of_pages|default:"-" }}</td>
                 </tr>
                 <tr>
                   <th scope="row">Year</th>
-                  <td>{{ d.publication_year }}</td>
+                  <td>{{ d.publication_year|default:"-" }}</td>
                 </tr>
               </tbody>
             </table>
diff --git a/ram/portal/templates/bookshelf_menu.html b/ram/portal/templates/bookshelf_menu.html
index 6d209a8..9c67e19 100644
--- a/ram/portal/templates/bookshelf_menu.html
+++ b/ram/portal/templates/bookshelf_menu.html
@@ -1,9 +1,9 @@
                 {% if bookshelf_menu %}
                 <li class="nav-item dropdown">
-                  <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownMenuLink" role="button" data-bs-toggle="dropdown" aria-expanded="false">
+                  <a class="nav-link dropdown-toggle" href="#" id="bookshelfDropdownMenuLink" role="button" data-bs-toggle="dropdown" aria-expanded="false">
                     Bookshelf
                   </a>
-                  <ul class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
+                  <ul class="dropdown-menu" aria-labelledby="bookshelfDropdownMenuLink">
                     <li><a class="nav-link" href="{% url 'books' %}">Books</a></li>
                   </ul>
                 </li>
diff --git a/ram/portal/templates/flatpage_menu.html b/ram/portal/templates/flatpage_menu.html
index af5fc49..71267bf 100644
--- a/ram/portal/templates/flatpage_menu.html
+++ b/ram/portal/templates/flatpage_menu.html
@@ -1,9 +1,9 @@
                 {% if flatpage_menu %}
                 <li class="nav-item dropdown">
-                  <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownMenuLink" role="button" data-bs-toggle="dropdown" aria-expanded="false">
+                  <a class="nav-link dropdown-toggle" href="#" id="flatpageDropdownMenuLink" role="button" data-bs-toggle="dropdown" aria-expanded="false">
                     Articles
                   </a>
-                  <ul class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
+                  <ul class="dropdown-menu" aria-labelledby="flatpageDropdownMenuLink">
                   {% for m in flatpage_menu %}
                     <li><a class="dropdown-item" href="{{ m.get_absolute_url }}">{{ m.name }}</a></li>
                   {% endfor %}
diff --git a/ram/portal/templates/rollingstock.html b/ram/portal/templates/rollingstock.html
index fd8827a..38a7c42 100644
--- a/ram/portal/templates/rollingstock.html
+++ b/ram/portal/templates/rollingstock.html
@@ -164,11 +164,11 @@
                       </tr>
                       <tr>
                         <th scope="row">Production year</th>
-                        <td>{{ rolling_stock.production_year | default_if_none:"" }}</td>
+                        <td>{{ rolling_stock.production_year|default:"-" }}</td>
                       </tr>
                       <tr>
                         <th scope="row">Purchase date</th>
-                        <td>{{ rolling_stock.purchase_date | default_if_none:"" }}</td>
+                        <td>{{ rolling_stock.purchase_date|default:"-" }}</td>
                       </tr>
                     </tbody>
                   </table>
@@ -264,7 +264,7 @@
                       </tr>
                       <tr>
                         <th scope="row">Manufacturer</th>
-                        <td>{{ rolling_stock.decoder.manufacturer|default_if_none:"" }}</td>
+                        <td>{{ rolling_stock.decoder.manufacturer|default:"-" }}</td>
                       </tr>
                       <tr>
                         <th scope="row">Version</th>