{% extends "base.html" %}
{#-
Static Open Graph / Twitter card meta. We use a custom_dir override rather than
Material's per-page social plugin so the build does not pull in the
material[imaging] system-library (Cairo/Pango) dependency. The card image is a
single branded asset (docs/assets/social-preview.png, 1280x640) referenced at an
absolute URL — unfurlers (X / LinkedIn / Slack) require an absolute og:image.
`extrahead` is empty in Material's base.html, so these tags are purely additive.
-#}
{% block extrahead %}
{#- `page` is None on theme-rendered pages such as 404.html, so guard every
page.* access (default(..., true) also replaces empty strings). -#}
{% set _title = (page.title if page else none) | default(config.site_name, true) %}
{% set _descr = (page.meta.description if page and page.meta else none) | default(config.site_description, true) %}
{% set _url = (page.canonical_url if page else none) | default(config.site_url, true) %}
{% set _image = config.site_url ~ "assets/social-preview.png" %}
{% endblock %}