diff --git a/tasks/converter.rb b/tasks/converter.rb
index e8ea2550..a94ee0c4 100644
--- a/tasks/converter.rb
+++ b/tasks/converter.rb
@@ -295,7 +295,8 @@ class Converter
 
   def replace_escaping(less)
     less = less.gsub(/\~"([^"]+)"/, '#{\1}') # Get rid of ~"" escape
-    less.gsub!(/\${([^}]+)}/, '$\1') # Get rid of @{} escape
+    less.gsub!(/\$\{([^}]+)\}/, '$\1') # Get rid of @{} escape
+    less.gsub!(/"([^"\n]*)(\$[\w\-]+)([^"\n]*)"/, '"\1#{\2}\3"') # interpolate variable in string, e.g. url("$file-1x") => url("#{$file-1x}")
     less.gsub(/(\W)e\(%\("?([^"]*)"?\)\)/, '\1\2') # Get rid of e(%("")) escape
   end
 
diff --git a/vendor/assets/stylesheets/bootstrap/_buttons.scss b/vendor/assets/stylesheets/bootstrap/_buttons.scss
index 4a5a35fa..ecbab5d1 100644
--- a/vendor/assets/stylesheets/bootstrap/_buttons.scss
+++ b/vendor/assets/stylesheets/bootstrap/_buttons.scss
@@ -123,7 +123,7 @@
 .btn-large {
   padding: $padding-large-vertical $padding-large-horizontal;
   font-size: $font-size-large;
-  line-height: 1.33; // ensure even-numbered height of butotn next to large input
+  line-height: 1.33; // ensure even-numbered height of button next to large input
   border-radius: $border-radius-large;
 }
 .btn-small,
diff --git a/vendor/assets/stylesheets/bootstrap/_mixins.scss b/vendor/assets/stylesheets/bootstrap/_mixins.scss
index 0ba0117a..91621c2a 100644
--- a/vendor/assets/stylesheets/bootstrap/_mixins.scss
+++ b/vendor/assets/stylesheets/bootstrap/_mixins.scss
@@ -158,9 +158,9 @@
 // Default value is `visible`, but can be changed to `hidden`
 // See git pull https://github.com/dannykeane/bootstrap.git backface-visibility for examples
 @mixin backface-visibility($visibility){
-	-webkit-backface-visibility: $visibility;
-	   -moz-backface-visibility: $visibility;
-	        backface-visibility: $visibility;
+  -webkit-backface-visibility: $visibility;
+     -moz-backface-visibility: $visibility;
+          backface-visibility: $visibility;
 }
 
 // Background clipping
@@ -230,6 +230,7 @@
 // --------------------------------------------------
 
 
+
 // Horizontal gradient, from left to right
 //
 // Creates two color stops, start and end, by specifying a color and position for each color stop.
@@ -300,6 +301,7 @@
   background-image: linear-gradient($angle, rgba(255,255,255,.15) 25%, transparent 25%, transparent 50%, rgba(255,255,255,.15) 50%, rgba(255,255,255,.15) 75%, transparent 75%, transparent);
 }
 
+
 // Reset filters for IE
 //
 // When you need to remove a gradient background, don't forget to use this to reset
@@ -315,7 +317,7 @@
 
 // Short retina mixin for setting background-image and -size
 @mixin img-retina($file-1x, $file-2x, $width-1x, $height-1x) {
-  background-image: url("${file-1x}");
+  background-image: url("#{$file-1x}");
 
   @media
   only screen and (-webkit-min-device-pixel-ratio: 2),
@@ -324,7 +326,7 @@
   only screen and (        min-device-pixel-ratio: 2),
   only screen and (                min-resolution: 192dpi),
   only screen and (                min-resolution: 2dppx) {
-    background-image: url("${file-2x}");
+    background-image: url("#{$file-2x}");
     background-size: $width-1x $height-1x;
   }
 }
@@ -403,7 +405,7 @@
 // Navbar vertical align
 // -------------------------
 // Vertically center elements in the navbar.
-// Example: an element has a height of 30px, so write out `@include navbarVerticalAlign(30px);` to calculate the appropriate top margin.
+// Example: an element has a height of 30px, so write out `.navbar-vertical-align(30px);` to calculate the appropriate top margin.
 @mixin navbar-vertical-align($element-height) {
   margin-top: (($navbar-height - $element-height) / 2);
   margin-bottom: (($navbar-height - $element-height) / 2);
@@ -421,7 +423,7 @@
 // Responsive utilities
 // -------------------------
 // More easily include all the states for responsive-utilities.less.
-// $parent hack because sass doesn't support tr& (without space)
+// [converter] $parent hack
 @mixin responsive-visibility($parent) {
   #{$parent} { display: block !important; }
   tr#{$parent} { display: table-row !important; }
@@ -429,6 +431,7 @@
   td#{$parent} { display: table-cell !important; }
 }
 
+// [converter] $parent hack
 @mixin responsive-invisibility($parent) {
   #{$parent} { display: none !important; }
   tr#{$parent} { display: none !important; }