diff --git a/internal/handlers/source_detail_test.go b/internal/handlers/source_detail_test.go
index faa945e..ad79ed2 100644
--- a/internal/handlers/source_detail_test.go
+++ b/internal/handlers/source_detail_test.go
@@ -241,3 +241,37 @@ func TestHandleSourceDetail_RendersNamedTargetFields(
 	assert.Contains(t, body, "(unavailable)")
 	assert.NotContains(t, body, "beak")
 }
+
+// TestHandleSourceDetail_FitsWideAndNarrowWindows pins the webhook
+// page's maximum width at 108rem (1728 px), half again the 72rem of
+// max-w-6xl that the webhook list and the event log use, so an
+// entrypoint URL fits on one line in a 1920-pixel window; and the
+// wrapping of its title row, so the buttons beside the title do not
+// push a phone-width window into scrolling sideways.
+func TestHandleSourceDetail_FitsWideAndNarrowWindows(t *testing.T) {
+	t.Parallel()
+
+	var (
+		h    *handlers.Handlers
+		sess *session.Session
+		db   *database.Database
+	)
+
+	app := newTestApp(t, &h, &sess, &db)
+	app.RequireStart()
+
+	t.Cleanup(app.RequireStop)
+
+	wh := seedWebhook(t, db)
+
+	body := renderSourceDetailPage(t, h, sess, wh.ID)
+
+	assert.Contains(
+		t, body,
+		`<div class="mx-auto px-6 py-8" style="max-width: 108rem"`,
+	)
+	assert.Contains(
+		t, body,
+		`<div class="flex flex-wrap justify-between items-center gap-2 mt-2">`,
+	)
+}
diff --git a/templates/source_detail.html b/templates/source_detail.html
index 7b4abf4..2a89922 100644
--- a/templates/source_detail.html
+++ b/templates/source_detail.html
@@ -3,10 +3,14 @@
 {{define "title"}}{{.Webhook.Name}} - Webhooker{{end}}
 
 {{define "content"}}
-<div class="max-w-6xl mx-auto px-6 py-8" x-data="{ showAddEntrypoint: false, showAddTarget: false }">
+<!-- 108rem, half again the 72rem (max-w-6xl) of the webhook list, the
+     event log, the navbar and the footer, so an entrypoint URL fits on
+     one line. An inline style, because the committed tailwind.css has
+     no class this wide. -->
+<div class="mx-auto px-6 py-8" style="max-width: 108rem" x-data="{ showAddEntrypoint: false, showAddTarget: false }">
     <div class="mb-6">
         <a href="/hooks" class="text-sm text-primary-600 hover:text-primary-700">&larr; Back to webhooks</a>
-        <div class="flex justify-between items-center mt-2">
+        <div class="flex flex-wrap justify-between items-center gap-2 mt-2">
             <div>
                 <h1 class="text-2xl font-medium text-gray-900">{{.Webhook.Name}}</h1>
                 {{if .Webhook.Description}}