diff --git a/data/templates/styles.html b/data/templates/styles.html
index 9e253e3e1..800f63c7a 100644
--- a/data/templates/styles.html
+++ b/data/templates/styles.html
@@ -1,3 +1,6 @@
+/* Default styles provided by pandoc.
+** See https://pandoc.org/MANUAL.html#variables-for-html for config info.
+*/
 $if(document-css)$
 html {
 $if(mainfont)$
diff --git a/test/s5-basic.html b/test/s5-basic.html
index 32b578779..4a0f297a8 100644
--- a/test/s5-basic.html
+++ b/test/s5-basic.html
@@ -11,6 +11,9 @@
   <meta name="date" content="2006-07-15" />
   <title>My S5 Document</title>
   <style type="text/css">
+    /* Default styles provided by pandoc.
+    ** See https://pandoc.org/MANUAL.html#variables-for-html for config info.
+    */
     code{white-space: pre-wrap;}
     span.smallcaps{font-variant: small-caps;}
     div.columns{display: flex; gap: min(4vw, 1.5em);}
diff --git a/test/s5-fancy.html b/test/s5-fancy.html
index 8e130823e..3a9bf0246 100644
--- a/test/s5-fancy.html
+++ b/test/s5-fancy.html
@@ -11,6 +11,9 @@
   <meta name="date" content="2006-07-15" />
   <title>My S5 Document</title>
   <style type="text/css">
+    /* Default styles provided by pandoc.
+    ** See https://pandoc.org/MANUAL.html#variables-for-html for config info.
+    */
     code{white-space: pre-wrap;}
     span.smallcaps{font-variant: small-caps;}
     div.columns{display: flex; gap: min(4vw, 1.5em);}
diff --git a/test/s5-inserts.html b/test/s5-inserts.html
index 491a10849..3c851f1e8 100644
--- a/test/s5-inserts.html
+++ b/test/s5-inserts.html
@@ -9,6 +9,9 @@
   <meta name="date" content="2006-07-15" />
   <title>My S5 Document</title>
   <style type="text/css">
+    /* Default styles provided by pandoc.
+    ** See https://pandoc.org/MANUAL.html#variables-for-html for config info.
+    */
     code{white-space: pre-wrap;}
     span.smallcaps{font-variant: small-caps;}
     div.columns{display: flex; gap: min(4vw, 1.5em);}
diff --git a/test/writer.html4 b/test/writer.html4
index 4b4672267..5e54fd980 100644
--- a/test/writer.html4
+++ b/test/writer.html4
@@ -9,6 +9,9 @@
   <meta name="date" content="2006-07-17" />
   <title>Pandoc Test Suite</title>
   <style type="text/css">
+    /* Default styles provided by pandoc.
+    ** See https://pandoc.org/MANUAL.html#variables-for-html for config info.
+    */
     html {
       color: #1a1a1a;
       background-color: #fdfdfd;
diff --git a/test/writer.html5 b/test/writer.html5
index 4c77a1fe9..a7c06813a 100644
--- a/test/writer.html5
+++ b/test/writer.html5
@@ -9,6 +9,9 @@
   <meta name="dcterms.date" content="2006-07-17" />
   <title>Pandoc Test Suite</title>
   <style>
+    /* Default styles provided by pandoc.
+    ** See https://pandoc.org/MANUAL.html#variables-for-html for config info.
+    */
     html {
       color: #1a1a1a;
       background-color: #fdfdfd;