diff --git a/src/index.css b/src/index.css
index f265d15c..2b06b8eb 100644
--- a/src/index.css
+++ b/src/index.css
@@ -233,6 +233,9 @@ select.plain {
   background-color: transparent;
 }
 
+pre {
+  tab-size: 2;
+}
 pre code,
 code {
   font-size: 90%;