diff --git a/tiddlywiki5/styles.css b/tiddlywiki5/styles.css
index ac98ef88a..878fcc8fb 100644
--- a/tiddlywiki5/styles.css
+++ b/tiddlywiki5/styles.css
@@ -44,6 +44,10 @@ pre {
 	white-space: pre;
 	white-space: pre-wrap;
 	word-wrap: break-word;
+    -moz-tab-size: 4;
+    -webkit-tab-size: 4;
+    -o-tab-size: 4;
+    tab-size: 4;
 }
 article {
 }