Improve Rainbow Pool filter form styles

app/assets/stylesheets/pet_types/index.sass

@@ -1,5 +1,21 @@
 @import "../partials/clean/constants"
 
+.pet-filters
+	fieldset
+		display: flex
+		flex-direction: row
+		align-items: center
+		justify-content: center
+		gap: .5em
+
+	legend
+		display: contents
+		font-weight: bold
+
+[role=navigation]
+	margin-block: .5em
+	text-align: center
+
 .pet-types
 	list-style-type: none
 	display: flex

app/views/pet_types/index.html.haml

@@ -1,10 +1,12 @@
 - title "Rainbow Pool"
 - use_responsive_design
 
-= form_with method: :get do |form|
-    = form.select :color, @color_names, selected: @selected_color&.human_name, include_blank: "Color…"
-    = form.select :species, @species_names, selected: @selected_species&.human_name, include_blank: "Species…"
-    = form.submit "Filter"
+= form_with method: :get, class: "pet-filters" do |form|
+    %fieldset
+        %legend Filter by:
+        = form.select :color, @color_names, selected: @selected_color&.human_name, include_blank: "Color…"
+        = form.select :species, @species_names, selected: @selected_species&.human_name, include_blank: "Species…"
+        = form.submit "Go"
 
 = will_paginate @pet_types