diff --git a/style.css b/style.css
index 6664b5f..04f321a 100644
--- a/style.css
+++ b/style.css
@@ -380,4 +380,11 @@
       margin: 0;
       padding: 0;
     }
+  }
+
+  /* A heading as the first line of a Callout keeps its prose top margin on
+     the deployed build (the prose first-child reset doesn't win inside the
+     callout), adding an unwanted gap. Zero it out. */
+  .callout .prose > :first-child {
+    margin-top: 0;
   }
\ No newline at end of file