diff --git a/main.css b/main.css
index 11a6b7a..670e529 100644
--- a/main.css
+++ b/main.css
@@ -37,7 +37,8 @@ border:1px solid #CCC}
 pre{
 background:#EEE;padding:1rem;
 white-space:pre-wrap;overflow-x:auto;
-border:1px solid #DDD;border-radius:6px}
+border:1px solid #DDD;border-radius:6px;
+-moz-tab-size:4;-o-tab-size:4;tab-size:4}
 .pre--small{font-size:.9rem;line-height:1.3rem}
 code{
 background:#EEE;padding:.05rem .4rem;