diff --git a/docs/assets/css/bootstrap-responsive.css b/docs/assets/css/bootstrap-responsive.css
index 1c454de0f9..fcc4967600 100644
--- a/docs/assets/css/bootstrap-responsive.css
+++ b/docs/assets/css/bootstrap-responsive.css
@@ -107,6 +107,7 @@
   }
   [class*="span"] {
     float: left;
+    min-height: 1px;
     margin-left: 30px;
   }
   .container,
@@ -453,6 +454,7 @@
   }
   [class*="span"] {
     float: left;
+    min-height: 1px;
     margin-left: 20px;
   }
   .container,
diff --git a/docs/assets/css/bootstrap.css b/docs/assets/css/bootstrap.css
index 5595e24448..ce6d27a56b 100644
--- a/docs/assets/css/bootstrap.css
+++ b/docs/assets/css/bootstrap.css
@@ -215,6 +215,7 @@ a:hover {
 
 [class*="span"] {
   float: left;
+  min-height: 1px;
   margin-left: 20px;
 }
 
diff --git a/less/mixins.less b/less/mixins.less
index 26ebbd82f3..785ac6c2e8 100644
--- a/less/mixins.less
+++ b/less/mixins.less
@@ -585,6 +585,7 @@
 
     [class*="span"] {
       float: left;
+      min-height: 1px; // prevent collapsing columns
       margin-left: @gridGutterWidth;
     }