oliverdavies.uk/source/_partials/title.html

{% set separator = '|' %}
{% spaceless %}<title>
  {% if page.full_title %}
    {{ page.full_title }}
  {% elseif page.title and site.title %}
    {{ page.title }} {{ separator }} {{ site.title }}
  {% elseif site.title %}
    {% if site.subtitle %}
      {{ site.subtitle }} {{ separator }} {{ site.title }}
    {% else %}
      {{ site.title }}
    {% endif %}
  {% endif %}
</title>{% endspaceless %}