Fix lightboxes and scss mixins

app/coffee/modules/common/lightboxes.coffee

@@ -38,6 +38,8 @@ class LightboxService extends taiga.Service
     constructor: (@animationFrame, @q) ->
 
     open: ($el) ->
+        if _.isString($el)
+            $el = $($el)
         defered = @q.defer()
 
         lightboxContent = $el.children().not(".close")
@@ -63,6 +65,8 @@ class LightboxService extends taiga.Service
         return defered.promise
 
     close: ($el) ->
+        if _.isString($el)
+            $el = $($el)
         docEl = angular.element(document)
         docEl.off(".lightbox")
         docEl.off(".keyboard-navigation") # Hack: to fix problems in the WYSIWYG textareas when press ENTER

app/styles/dependencies/mixins.scss

@@ -17,6 +17,15 @@
     }
 }
 
+@mixin placeholder {
+  $placeholders: ":-webkit-input" ":-moz" "-moz" "-ms-input";
+  @each $placeholder in $placeholders {
+    &:#{$placeholder}-placeholder {
+      @content;
+    }
+  }
+}
+
 @mixin slide($max, $overflow, $min: 0) {
     max-height: $min;
     transition: max-height .5s ease-in;