Dissociate .sideNav--horizontal from @expand-side-nav

less/common/sideNav.less

@@ -11,7 +11,6 @@
 // .dropdown-select into a plain list.
 @media @expand-side-nav {
   .sideNav {
-    // Expand the dropdown-select component into a normal nav list.
     & .Dropdown--select {
       display: block;
 
@@ -48,10 +47,33 @@
   }
 }
 
-.sideNav--horizontal {}
+@media @tablet {
+  .sideNav {
+    .sideNav--horizontal();
+  }
+}
 
-@media @expand-side-nav {
-  .sideNav--horizontal {
+@media @desktop-up {
+  .sideNav {
+    float: left;
+
+    &, > ul {
+      width: 190px;
+    }
+    > ul {
+      margin-top: 30px;
+
+      &.affix {
+        top: @header-height;
+      }
+      > li {
+        margin-bottom: 10px;
+      }
+    }
+  }
+}
+
+.sideNav--horizontal {
   padding: 15px 0;
   white-space: nowrap;
   overflow: auto;
@@ -86,33 +108,6 @@
   .affix {
     position: static;
   }
-  }
-
-  @media @tablet {
-    .sideNav {
-      .sideNav--horizontal();
-    }
-  }
-}
-
-@media @desktop-up {
-  .sideNav {
-    float: left;
-
-    &, > ul {
-      width: 190px;
-    }
-    > ul {
-      margin-top: 30px;
-
-      &.affix {
-        top: @header-height;
-      }
-      > li {
-        margin-bottom: 10px;
-      }
-    }
-  }
 }
 
 @media @phone, @tablet {