diff --git a/docs/assets/bootstrap.zip b/docs/assets/bootstrap.zip
index 1fc44889d8..1636eb0628 100644
Binary files a/docs/assets/bootstrap.zip and b/docs/assets/bootstrap.zip differ
diff --git a/docs/assets/css/bootstrap.css b/docs/assets/css/bootstrap.css
index a363a77598..03a165545d 100644
--- a/docs/assets/css/bootstrap.css
+++ b/docs/assets/css/bootstrap.css
@@ -1949,10 +1949,10 @@ table .span24 {
   background-image: -o-linear-gradient(top, #ffffff, #e6e6e6);
   background-image: linear-gradient(top, #ffffff, #e6e6e6);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ffffff', endColorstr='#e6e6e6', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
   border-color: #e6e6e6 #e6e6e6 #bfbfbf;
   border-color: rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.25);
-  filter: progid:DXImageTransform.Microsoft.gradient(enabled = false);
+  filter: progid:dximagetransform.microsoft.gradient(enabled=false);
   border: 1px solid #cccccc;
   border-bottom-color: #b3b3b3;
   -webkit-border-radius: 4px;
@@ -2071,10 +2071,10 @@ table .span24 {
   background-image: -o-linear-gradient(top, #0088cc, #0055cc);
   background-image: linear-gradient(top, #0088cc, #0055cc);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#0088cc', endColorstr='#0055cc', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
   border-color: #0055cc #0055cc #003580;
   border-color: rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.25);
-  filter: progid:DXImageTransform.Microsoft.gradient(enabled = false);
+  filter: progid:dximagetransform.microsoft.gradient(enabled=false);
 }
 .btn-primary:hover,
 .btn-primary:active,
@@ -2096,10 +2096,10 @@ table .span24 {
   background-image: -o-linear-gradient(top, #fbb450, #f89406);
   background-image: linear-gradient(top, #fbb450, #f89406);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#fbb450', endColorstr='#f89406', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
   border-color: #f89406 #f89406 #ad6704;
   border-color: rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.25);
-  filter: progid:DXImageTransform.Microsoft.gradient(enabled = false);
+  filter: progid:dximagetransform.microsoft.gradient(enabled=false);
 }
 .btn-warning:hover,
 .btn-warning:active,
@@ -2121,10 +2121,10 @@ table .span24 {
   background-image: -o-linear-gradient(top, #ee5f5b, #bd362f);
   background-image: linear-gradient(top, #ee5f5b, #bd362f);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ee5f5b', endColorstr='#bd362f', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
   border-color: #bd362f #bd362f #802420;
   border-color: rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.25);
-  filter: progid:DXImageTransform.Microsoft.gradient(enabled = false);
+  filter: progid:dximagetransform.microsoft.gradient(enabled=false);
 }
 .btn-danger:hover,
 .btn-danger:active,
@@ -2146,10 +2146,10 @@ table .span24 {
   background-image: -o-linear-gradient(top, #62c462, #51a351);
   background-image: linear-gradient(top, #62c462, #51a351);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#62c462', endColorstr='#51a351', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
   border-color: #51a351 #51a351 #387038;
   border-color: rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.25);
-  filter: progid:DXImageTransform.Microsoft.gradient(enabled = false);
+  filter: progid:dximagetransform.microsoft.gradient(enabled=false);
 }
 .btn-success:hover,
 .btn-success:active,
@@ -2171,10 +2171,10 @@ table .span24 {
   background-image: -o-linear-gradient(top, #5bc0de, #2f96b4);
   background-image: linear-gradient(top, #5bc0de, #2f96b4);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#5bc0de', endColorstr='#2f96b4', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
   border-color: #2f96b4 #2f96b4 #1f6377;
   border-color: rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.25);
-  filter: progid:DXImageTransform.Microsoft.gradient(enabled = false);
+  filter: progid:dximagetransform.microsoft.gradient(enabled=false);
 }
 .btn-info:hover,
 .btn-info:active,
@@ -2196,10 +2196,10 @@ table .span24 {
   background-image: -o-linear-gradient(top, #555555, #222222);
   background-image: linear-gradient(top, #555555, #222222);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#555555', endColorstr='#222222', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
   border-color: #222222 #222222 #000000;
   border-color: rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.25);
-  filter: progid:DXImageTransform.Microsoft.gradient(enabled = false);
+  filter: progid:dximagetransform.microsoft.gradient(enabled=false);
 }
 .btn-inverse:hover,
 .btn-inverse:active,
@@ -2725,7 +2725,7 @@ input[type="submit"].btn.btn-small {
   background-image: -o-linear-gradient(top, #333333, #222222);
   background-image: linear-gradient(top, #333333, #222222);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#333333', endColorstr='#222222', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
   -webkit-border-radius: 4px;
   -moz-border-radius: 4px;
   border-radius: 4px;
@@ -2750,10 +2750,10 @@ input[type="submit"].btn.btn-small {
   background-image: -o-linear-gradient(top, #333333, #222222);
   background-image: linear-gradient(top, #333333, #222222);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#333333', endColorstr='#222222', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
   border-color: #222222 #222222 #000000;
   border-color: rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.1) rgba(0, 0, 0, 0.25);
-  filter: progid:DXImageTransform.Microsoft.gradient(enabled = false);
+  filter: progid:dximagetransform.microsoft.gradient(enabled=false);
   -webkit-box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.1), 0 1px 0 rgba(255, 255, 255, 0.075);
   -moz-box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.1), 0 1px 0 rgba(255, 255, 255, 0.075);
   box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.1), 0 1px 0 rgba(255, 255, 255, 0.075);
@@ -3055,7 +3055,7 @@ input[type="submit"].btn.btn-small {
   background-image: -o-linear-gradient(top, #ffffff, #f5f5f5);
   background-image: linear-gradient(top, #ffffff, #f5f5f5);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ffffff', endColorstr='#f5f5f5', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
   border: 1px solid #ddd;
   -webkit-border-radius: 3px;
   -moz-border-radius: 3px;
@@ -3630,7 +3630,7 @@ a.thumbnail:hover {
   background-image: -o-linear-gradient(top, #f5f5f5, #f9f9f9);
   background-image: linear-gradient(top, #f5f5f5, #f9f9f9);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#f5f5f5', endColorstr='#f9f9f9', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
   -webkit-box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.1);
   -moz-box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.1);
   box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.1);
@@ -3653,7 +3653,7 @@ a.thumbnail:hover {
   background-image: -o-linear-gradient(top, #149bdf, #0480be);
   background-image: linear-gradient(top, #149bdf, #0480be);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#149bdf', endColorstr='#0480be', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
   -webkit-box-shadow: inset 0 -1px 0 rgba(0, 0, 0, 0.15);
   -moz-box-shadow: inset 0 -1px 0 rgba(0, 0, 0, 0.15);
   box-shadow: inset 0 -1px 0 rgba(0, 0, 0, 0.15);
@@ -3693,7 +3693,7 @@ a.thumbnail:hover {
   background-image: -o-linear-gradient(top, #ee5f5b, #c43c35);
   background-image: linear-gradient(top, #ee5f5b, #c43c35);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ee5f5b', endColorstr='#c43c35', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
 }
 .progress-danger.progress-striped .bar {
   background-color: #ee5f5b;
@@ -3713,7 +3713,7 @@ a.thumbnail:hover {
   background-image: -o-linear-gradient(top, #62c462, #57a957);
   background-image: linear-gradient(top, #62c462, #57a957);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#62c462', endColorstr='#57a957', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
 }
 .progress-success.progress-striped .bar {
   background-color: #62c462;
@@ -3733,7 +3733,7 @@ a.thumbnail:hover {
   background-image: -o-linear-gradient(top, #5bc0de, #339bb9);
   background-image: linear-gradient(top, #5bc0de, #339bb9);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#5bc0de', endColorstr='#339bb9', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
 }
 .progress-info.progress-striped .bar {
   background-color: #5bc0de;
@@ -3753,7 +3753,7 @@ a.thumbnail:hover {
   background-image: -o-linear-gradient(top, #fbb450, #f89406);
   background-image: linear-gradient(top, #fbb450, #f89406);
   background-repeat: repeat-x;
-  filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#fbb450', endColorstr='#f89406', GradientType=0);
+  filter: progid:dximagetransform.microsoft.gradient(startColorstr=#ffffff, endColorstr=#e6e6e6, GradientType=0);
 }
 .progress-warning.progress-striped .bar {
   background-color: #fbb450;
diff --git a/less/mixins.less b/less/mixins.less
index bba7544528..47d467243b 100644
--- a/less/mixins.less
+++ b/less/mixins.less
@@ -283,7 +283,7 @@
 // Opacity
 .opacity(@opacity: 100) {
   opacity: @opacity / 100;
-   filter: e(%("alpha(opacity=%d)", @opacity));
+   filter: ~"alpha(opacity=@{opacity})";
 }
 
 
@@ -320,7 +320,7 @@
     background-image: -o-linear-gradient(left, @startColor, @endColor); // Opera 11.10
     background-image: linear-gradient(left, @startColor, @endColor); // Le standard
     background-repeat: repeat-x;
-    filter: e(%("progid:DXImageTransform.Microsoft.gradient(startColorstr='%d', endColorstr='%d', GradientType=1)",@startColor,@endColor)); // IE9 and down
+    filter: progid:DXImageTransform.Microsoft.gradient(startColorstr=@startColor, endColorstr=@endColor, GradientType=1); // IE9 and down
   }
   .vertical(@startColor: #555, @endColor: #333) {
     background-color: mix(@startColor, @endColor, 60%);
@@ -331,7 +331,7 @@
     background-image: -o-linear-gradient(top, @startColor, @endColor); // Opera 11.10
     background-image: linear-gradient(top, @startColor, @endColor); // The standard
     background-repeat: repeat-x;
-    filter: e(%("progid:DXImageTransform.Microsoft.gradient(startColorstr='%d', endColorstr='%d', GradientType=0)",@startColor,@endColor)); // IE9 and down
+    filter: progid:DXImageTransform.Microsoft.gradient(startColorstr=@startColor, endColorstr=@endColor, GradientType=0); // IE9 and down
   }
   .directional(@startColor: #555, @endColor: #333, @deg: 45deg) {
     background-color: @endColor;
@@ -351,7 +351,7 @@
     background-image: -o-linear-gradient(@startColor, @midColor @colorStop, @endColor);
     background-image: linear-gradient(@startColor, @midColor @colorStop, @endColor);
     background-repeat: no-repeat;
-    filter: e(%("progid:DXImageTransform.Microsoft.gradient(startColorstr='%d', endColorstr='%d', GradientType=0)",@startColor,@endColor)); // IE9 and down, gets no color-stop at all for proper fallback
+    filter: progid:DXImageTransform.Microsoft.gradient(startColorstr=@startColor, endColorstr=@endColor, GradientType=0); // IE9 and down, gets no color-stop at all for proper fallback
   }
   .radial(@innerColor: #555, @outerColor: #333)  {
     background-color: @outerColor;
@@ -374,7 +374,7 @@
 }
 // Reset filters for IE
 .reset-filter() {
-  filter: e(%("progid:DXImageTransform.Microsoft.gradient(enabled = false)"));
+  filter: progid:DXImageTransform.Microsoft.gradient(enabled = false);
 }