title is no longer required in frontpage.json

As a result, the jumbotron is completely hidden if none of
title, subtitle, text are set and show_input is False

nbviewer/frontpage.schema.json

@@ -29,6 +29,5 @@
        ]
      }
    }
- },
- "required": ["title"]
+ }
 }

nbviewer/handlers.py

@@ -35,9 +35,9 @@ class IndexHandler(BaseHandler):
     def get(self):
         self.finish(self.render_template(
             'index.html',
-            title=self.frontpage_setup['title'],
+            title=self.frontpage_setup.get('title', None),
             subtitle=self.frontpage_setup.get('subtitle', None),
-            text=self.frontpage_setup.get('text',None),
+            text=self.frontpage_setup.get('text', None),
             show_input=self.frontpage_setup.get('show_input', True),
             sections=self.frontpage_setup.get('sections', [])))
 

nbviewer/templates/index.html

@@ -1,11 +1,10 @@
 {% extends "layout.html" %}
 
 {% block body %}
+  {% if title or subtitle or text or show_input %}
   <header class="jumbotron masthead">
-    <h1>{{ title }}</h1>
-    {% if subtitle %}
-    <h2>{{ subtitle }}</h2>
-    {% endif %}
+    {% if title %}<h1>{{ title }}</h1>{% endif %}
+    {% if subtitle %}<h2>{{ subtitle }}</h2>{% endif %}
     {% if text %}
     {{ text | markdown | safe }}
     {% endif %}
@@ -31,6 +30,7 @@ <h2>{{ subtitle }}</h2>
     </div>
     {% endif %} 
   </header>
+  {% endif %}
 
   {% for section in sections %}
     <section>