diff --git a/theme.js b/theme.js
index 9c5dfaf..36a9aae 100644
--- a/theme.js
+++ b/theme.js
@@ -2,6 +2,9 @@ import { dark as theme } from 'mdx-deck/themes'
 
 export default {
     ...theme,
+    fontSizes: [
+        '0.75em', '1em', '1.3em', '1.7em', '2.5em'
+    ],
     css: {
         ...theme.css,
         'li > ul, li > ol': {