fix(feed): fix feed icons

src/sass/theme/components/_pageTop.scss

@@ -101,7 +101,7 @@ a.collapse-menu-link {
   display: inline-block;
   width: 14px;
   height: 13px;
-  @include bg-image('theme/palette.png');
+  @include bg('theme/palette.png');
   background-size: cover;
 }
 

src/sass/theme/conf/_mixins.scss

@@ -24,10 +24,14 @@
 @mixin bg-nr($relativeUrl) {
   background: url($images-root + $relativeUrl) no-repeat 0 0;
 }
-@mixin bg-image($relativeUrl) {
+@mixin bg($relativeUrl) {
   background: url($images-root + $relativeUrl);
 }
 
+@mixin bg-image($relativeUrl) {
+  background-image: url($images-root + $relativeUrl);
+}
+
 @mixin main-background() {
   $mainBgUrl: $images-root + 'green-bg.jpg';
   background: url($mainBgUrl) no-repeat top center fixed;