fix(interior-left-nav): fixed background color bug on the left nav (#318)

Author: marijohannessen

src/components/interior-left-nav/interior-left-nav.scss

@@ -219,7 +219,7 @@
 
     .left-nav-list__item--active > .left-nav-list__item-link {
       position: relative;
-      background-color: #fff;
+      background-color: transparent;
 
       &:before {
         top: 0;