docs/theme/overrides/partials/integrations/analytics/fathom.html
<!-- Determine analytics property -->
{% if config.extra.analytics %}
{% set key = config.extra.analytics.key | d("", true) %}
{% set domain = config.extra.analytics.domain | d("cdn.usefathom.com", true) %}
{% endif %}
<script src="https://{{ domain }}/script.js" data-site="{{ key }}" defer></script>