set global margin on the main app grid

+ refactor margins and paddings in some components

src/views/FolderView.vue

@@ -51,7 +51,6 @@ onBeforeRouteUpdate((to, from) => {
 
 #scrollable {
   overflow-y: auto;
-  height: calc(100% - $small);
   scrollbar-color: grey transparent;
 
   @include phone-only {

src/views/Playlists.vue

@@ -25,7 +25,6 @@ const pStore = usePStore();
   scrollbar-color: $gray2 transparent;
 
   .grid {
-    display: grid;
     grid-template-columns: repeat(auto-fill, minmax(10rem, 1fr));
     gap: 1rem;
   }