diff --git a/public/css/theme-auto-red.css b/public/css/theme-auto-red.css
index 4785067..8326f8a 100644
--- a/public/css/theme-auto-red.css
+++ b/public/css/theme-auto-red.css
@@ -74,7 +74,7 @@
     /* not needed: .repository .diff-detail-box */
     
     details {
-        background-color: var(--color-secondary-light-3); /* make collapsible elements easier to distinguish from main body */
+        background-color: var(--color-secondary-light-2); /* make collapsible elements easier to distinguish from main body */
         border-radius: 4px; /* same as code blocks */
         padding: .2em .4em; /* same as code blocks */
     }
diff --git a/public/css/theme-red.css b/public/css/theme-red.css
index 165aaed..1a1dcbb 100644
--- a/public/css/theme-red.css
+++ b/public/css/theme-red.css
@@ -71,7 +71,7 @@
 /* not needed: .repository .diff-detail-box */
 
 details {
-    background-color: var(--color-secondary-light-3); /* make collapsible elements easier to distinguish from main body */
+    background-color: var(--color-secondary-light-2); /* make collapsible elements easier to distinguish from main body */
     border-radius: 4px; /* same as code blocks */
     padding: .2em .4em; /* same as code blocks */
 }