diff --git a/inst/reveal.js-5.1.0/css/theme/source/ids.scss b/inst/reveal.js-5.1.0/css/theme/source/ids.scss
index e97f0c7..b069d58 100644
--- a/inst/reveal.js-5.1.0/css/theme/source/ids.scss
+++ b/inst/reveal.js-5.1.0/css/theme/source/ids.scss
@@ -269,6 +269,16 @@
   }
 }
 
+// Nested list items are set progressively smaller, both to emphasise the
+// hierarchy and to keep deeply nested lists from visually competing with the
+// first level. The em size compounds down the nesting levels, so each deeper
+// level is 80% of its parent (level 2: 80%, level 3: 64%, level 4: 51%).
+// Markers and the hanging indentation (padding-left: 0.7em above) scale with
+// the text automatically.
+.reveal li li {
+  font-size: 0.8em;
+}
+
 
 /*********************************************
  * FOOTER
diff --git a/inst/reveal.js-5.1.0/dist/theme/ids.css b/inst/reveal.js-5.1.0/dist/theme/ids.css
index ef9e1f5..3a5dcb0 100644
--- a/inst/reveal.js-5.1.0/dist/theme/ids.css
+++ b/inst/reveal.js-5.1.0/dist/theme/ids.css
@@ -482,6 +482,15 @@
   color: var(--r-list-bullet-color) !important;
 }
 
+/* Nested list items are set progressively smaller, both to emphasise the
+   hierarchy and to keep deeply nested lists from visually competing with the
+   first level. The em size compounds down the nesting levels, so each deeper
+   level is 80% of its parent (level 2: 80%, level 3: 64%, level 4: 51%).
+   Markers and the hanging indentation scale with the text automatically. */
+.reveal li li {
+  font-size: 0.8em;
+}
+
 /*********************************************
  * FOOTER
  *********************************************/