diff --git a/default.scss b/default.scss
index 9c27b14..75f3321 100644
--- a/default.scss
+++ b/default.scss
@@ -15,6 +15,23 @@ pre {
     @include border-radius(3px);
     border: 1px solid $content-border-color;
     padding: 5px;
+    overflow-x: scroll;
+    counter-reset: line;
+
+    span {
+        display: block;
+
+        &:before {
+            counter-increment: line;
+            content: counter(line);
+            display: inline-block;
+            border-right: 1px solid #ddd;
+            padding: 0 .5em;
+            margin-right: .5em;
+            color: #888;
+            width: 30px;
+        }
+    }
 }
 
 article {