diff --git a/src/main/kotlin/html4tree/main.kt b/src/main/kotlin/html4tree/main.kt
index 4ad086a..8945d0b 100644
--- a/src/main/kotlin/html4tree/main.kt
+++ b/src/main/kotlin/html4tree/main.kt
@@ -24,6 +24,9 @@ main {
   max-width: 800px;
   margin: 0 auto;
 }
+h1 {
+  overflow-wrap: anywhere;
+}
 ul {
   list-style-type: none;
   padding-left: 0;
diff --git a/src/test/kotlin/html4tree/MainTest.kt b/src/test/kotlin/html4tree/MainTest.kt
index 68d344d..4e5eb0f 100644
--- a/src/test/kotlin/html4tree/MainTest.kt
+++ b/src/test/kotlin/html4tree/MainTest.kt
@@ -357,6 +357,10 @@ class MainTest {
         assertTrue(htmlContent.contains("prefers-reduced-motion"))
         assertTrue(htmlContent.contains("max-width: 800px;"))
         assertTrue(htmlContent.contains("margin: 0 auto;"))
+        assertTrue(
+            Regex("""h1\s*\{[^}]*overflow-wrap:\s*anywhere;""").containsMatchIn(htmlContent),
+            "long directory headings must wrap within narrow viewports"
+        )
     }
 
     @Test