diff --git a/source/_includes/horizontal-rule.html.twig b/source/_includes/horizontal-rule.html.twig
new file mode 100644
index 00000000..a2fec2fb
--- /dev/null
+++ b/source/_includes/horizontal-rule.html.twig
@@ -0,0 +1 @@
+<hr class="my-12 border-t border-gray-300 dark:border-gray-500"/>
diff --git a/source/_pages/drupal-testing.md b/source/_pages/drupal-testing.md
index f7455a2c..b672ffe8 100644
--- a/source/_pages/drupal-testing.md
+++ b/source/_pages/drupal-testing.md
@@ -32,7 +32,7 @@ I offer an interactive full-day workshop (previously presented at DrupalCamp Lon
 * Exercise: writing a new Drupal module from scratch with test-driven development.
 * Q&A
 
-<hr class="my-12 border-t border-gray-50"/>
+{% include "horizontal-rule" %}
 
 ## Dates and prices
 
@@ -48,7 +48,7 @@ Seats are available at {% if page.early %}an <span class="font-bold">early bird
     {% endembed %}
 </div>
 
-<hr class="my-12 border-t border-gray-50"/>
+{% include "horizontal-rule" %}
 
 ## Testimonials