specify language in the content

semantically more correct, since the menu is not really/always
translated

themes/bs3/templates/page.html

@@ -28,7 +28,7 @@
 {% endblock %}
 
 {% block content %}
-    <section id="content" class="body">
+<section id="content" class="body" lang="{{page.lang}}">
         <h1 class="entry-title">{{ page.title }}</h1>
         {% import 'includes/translations.html' as translations with context %}
         {{ translations.translations_for(page) }}