Simplify styling: combine cases

assets/scss/_sidebar-tree.scss

@@ -15,26 +15,21 @@
     }
   }
 
-  // Adjust height and padding when sidebar_search_disable is true
+  // Adjust height and padding when sidebar_search_disable is true, but only for
+  // >= `lg` views, because on tablet (`md`) and mobile (<= `sm`), the search
+  // box is displayed regardless of the value of sidebar_search_disable:
   &.td-sidebar-nav--search-disabled {
-    padding-top: 1rem;
+    @include media-breakpoint-up(lg) {
+      // There's no search box so add top padding
+      // and adjust max-height:
+      padding-top: 1rem;
 
-    @include media-breakpoint-up(md) {
       @supports (position: sticky) {
         max-height: calc(#{$_max-height} + 4.5rem);
       }
     }
   }
 
-  // Handle cases for tablet (`md`) and mobile (<= `sm`) where the search box is
-  // displayed regardless of the value of sidebar_search_disable:
-  @include media-breakpoint-down(lg) {
-    padding-top: 0 !important;
-    @supports (position: sticky) {
-      max-height: $_max-height !important;
-    }
-  }
-
   @include media-breakpoint-up(md) {
     display: block !important;
   }