Leadership calendar pdf styling

One thing to note @Scotchester and @virginiacc is that I changed the way you add custom CSS and JS. Now there is only one CSS or JS Jinja block and if you want to extend it you can do it easily using `{{ super() }}` like this:

```html
{% block css %}
  {{ super() }}

  /* my extra styles can go here */
  <link rel="stylesheet" href="moar-styles.css">

  <style>
   /* or here */
  </style>
{% endblock %}
```

If you want to NOT use the main.css file just leave out the call to `super()`.

Same with the `javascript` block.
I thought about `hr`, but according to the spec, that's for a "paragraph-level thematic break", so this isn't really that.