Uniform icon classes inside buttons

lib/music_library_web/live/scrobble_rules_live/index.html.heex

@@ -12,7 +12,7 @@
           size="sm"
           patch={~p"/scrobble-rules/new"}
         >
-          <.icon name="hero-plus" class="h-4 w-4 mr-2" aria-hidden="true" data-slot="icon" />
+          <.icon name="hero-plus" class="icon" aria-hidden="true" data-slot="icon" />
           {gettext("New Rule")}
         </.button>
         <.button
@@ -20,7 +20,7 @@
           size="sm"
           phx-click="apply_all_rules"
         >
-          <.icon name="hero-play" class="h-4 w-4 mr-2" />
+          <.icon name="hero-play" class="icon" />
           {gettext("Apply All")}
         </.button>
       </.button_group>