Easy Redesign in Rails: Run Old and New Side by Side with :variants

Rails variants are usually used to serve different views for devices — but you can use them for much more, like running a redesign side by side.Redesigning a mature Rails app can feel like a minefield. You're still pushing hotfixes to production, QA needs to validate existing behavior, and stakeholders want to compare the old and new versions side by side. Imagine being able to render both designs on the same page — safely, in the same app, with minimal code overhead and in production. That’s where :variants come in.