diff --git a/docs/assets/css/bootstrap-responsive.css b/docs/assets/css/bootstrap-responsive.css
index d234664421..d5b7e3c4e0 100644
--- a/docs/assets/css/bootstrap-responsive.css
+++ b/docs/assets/css/bootstrap-responsive.css
@@ -814,6 +814,13 @@
     width: auto;
     margin-left: 0;
   }
+  .span12,
+  .row-fluid .span12 {
+    width: 100%;
+    -webkit-box-sizing: border-box;
+       -moz-box-sizing: border-box;
+            box-sizing: border-box;
+  }
   .input-large,
   .input-xlarge,
   .input-xxlarge,
diff --git a/less/responsive-767px-max.less b/less/responsive-767px-max.less
index 18c96ee0b7..65e019a8fb 100644
--- a/less/responsive-767px-max.less
+++ b/less/responsive-767px-max.less
@@ -62,6 +62,11 @@
     width: auto;
     margin-left: 0;
   }
+  .span12,
+  .row-fluid .span12 {
+    width: 100%;
+    .box-sizing(border-box);
+  }
 
   // FORM FIELDS
   // -----------