fix(ui): replace static dropdown backgrounds with transparent mapping (#21728)

src/lib/components/admin/Settings/Evaluations/ArenaModelModal.svelte

@@ -350,7 +350,7 @@
 
 						<div class="flex items-center">
 							<select
-								class="dark:bg-gray-900 w-full py-1 text-sm rounded-lg bg-transparent {selectedModelId
+								class="w-full py-1 text-sm rounded-lg bg-transparent {selectedModelId
 									? ''
 									: 'text-gray-500'} placeholder:text-gray-300 dark:placeholder:text-gray-700 outline-hidden"
 								bind:value={selectedModelId}