diff --git a/doc/style.css b/doc/style.css
index a49fb87..4de2787 100644
--- a/doc/style.css
+++ b/doc/style.css
@@ -644,6 +644,7 @@ td,
     table.table 
 th
 {
+    border: solid 1px #c7c7c7;
     vertical-align: top;    
 }