Nunjucks component macro - NOTE: Had to use .twig file extension since Github Gists don't support .njk :(

hero.twig

{% macro hero(
        title="We Are Awesome",
        background_image="http://placehold.it/1000x400",
        cta_text="Find Out Why!",
        cta_href="/some/awesome-link.html"
        ) %}
  <div class="hero" {% if background_image %} style="background-image:url({{ background_image }})" {% endif %}>
    <h1 class="hero__title">{{ title }}</h1>
    {% if caller %}
      {{ caller() }}
    {% endif %}
    <a class="hero__cta button button--primary" href="{{ cta_href }}>{{ cta_text }}</a>
  </div>
{% endmacro %}

{# usage, rapid prototyping #}
{{ hero() }}

{# something with some context #}
{{ hero(title="We're super cool at that thing we do.") }}

{# passing in an html block #}
{% call hero(title="Three reasonse we're the best:") %}
  <div class="grid-row">
    <div class="grid-column-4">
      <h2>Industry Leadership</h2>
    </div>
    <div class="grid-column-4">
      <h2>Marketing Buzzword</h2>
    </div>
    <div class="grid-column-4">
      <h2>Cause we said so.</h2>
    </div>
  </div>
{% endcall %}