Cleanup nav-stacked .active state styles, remove unnecessary nesting

app/assets/stylesheets/common/admin/admin_base.scss

@@ -375,11 +375,6 @@ td.flaggers td {
   width: 18.018%;
   position: relative;
 
-  li a.active {
-    color: $secondary;
-    background-color: $quaternary;
-  }
-
   // The admin-nav becomes a slide-out menu at the mobile-nav breakpoint
   @media (max-width: $mobile-breakpoint) {
     position: absolute;

app/assets/stylesheets/common/base/rtl.scss

@@ -27,7 +27,7 @@
 
 // Changes the triangle arrow direction in .nav-stacked .active
 // The 'left' and 'right' in these selectors is not being flipped by r2.
-.rtl .nav-stacked .active > a::after {
+.rtl .nav-stacked a.active::after {
   border-left-color: transparent !important;
   border-right-color: $secondary !important;
 }

app/assets/stylesheets/common/components/navs.scss

@@ -76,6 +76,7 @@
     &.indent {
       padding-left: 15px;
     }
+  }
 
   a {
     margin: 0;
@@ -84,15 +85,12 @@
     line-height: 20px;
     cursor: pointer;
     color: $primary;
-    }
-  }
 
-  .active > a,
-  li > a.active {
+    &.active {
       color: $secondary;
       background-color: $quaternary;
 
-    &:after {
+      &::after {
         left: 90%;
         top: 33%;
         content: " ";
@@ -101,6 +99,7 @@
         border-left-color: $secondary;
       }
     }
+  }
 
   .count {
     font-size: 0.857em;

app/assets/stylesheets/desktop/user.scss

@@ -113,14 +113,19 @@
 
   .nav-stacked {
     background-color: transparent;
+
     li {
       border-bottom: none;
 
-      a {
-        color: dark-light-choose(scale-color($primary, $lightness: 40%), scale-color($secondary, $lightness: 40%));
+      &.archive {
+        padding-left: 15px;
+      }
     }
 
-      a.active {
+    a {
+      color: dark-light-choose(scale-color($primary, $lightness: 40%), scale-color($secondary, $lightness: 40%));
+
+      &.active {
         color: $primary;
         font-weight: bold;
         background-color: transparent;
@@ -129,9 +134,6 @@
           display: none;
         }
       }
-      &.archive {
-        padding-left: 15px;
-      }
     }
   }
 }