“Desktop preview / Phone preview” toggle

Step by step

1. On the Create club form, in step 3, find the live banner preview near the bottom of that step.
2. Click Desktop preview to see how your banner looks on a computer screen.
3. Click Phone preview to see how it looks on a phone-width screen instead.

This only resizes the preview box — it has no effect on what actually gets saved, so switch between them as often as you like.