Add missing styles (#14031)

packages/frontend/src/pages/announcement.vue

@@ -109,6 +109,15 @@ definePageMetadata(() => ({
 </script>
 
 <style lang="scss" module>
+.fadeEnterActive,
+.fadeLeaveActive {
+	transition: opacity 0.125s ease;
+}
+.fadeEnterFrom,
+.fadeLeaveTo {
+	opacity: 0;
+}
+
 .announcement {
 	padding: 16px;
 }