remove unwanted margin-right on .level-item at mobile breakpoint (#1153)

sass/components/level.sass

@@ -48,11 +48,13 @@
   flex-grow: 0
   flex-shrink: 0
   .level-item
-    &:not(:last-child)
-      margin-right: 0.75rem
     // Modifiers
     &.is-flexible
       flex-grow: 1
+    // Responsiveness
+    +tablet
+      &:not(:last-child)
+        margin-right: 0.75rem
 
 .level-left
   align-items: center