FIX: Update default_template.html (PR #9842)

This seems to fix some intermittent email rendering issues that were cropping up.

https://meta.discourse.org/t/migrating-from-drupal-community-firecore-com/149349/178?u=jordan.vidrine

GitHub

The title of this pull request changed from “Update default_template.html” to "FIX: Update default_template.html