The Starters input field shows a focus ring

The input field of the Starters card showed no sign that it had focus. A shopper who tapped or tabbed into it had nothing to tell them where their typing would go.

It now draws a 2 px ring along the field's edge while the shopper is in it. The ring takes the colour of your send button. When that colour has under 3:1 contrast against the field's background (a pale send button on a white field, say), the ring takes the field's text colour instead, so it always stands out from the field.

There's nothing to set: the ring follows the send button and input field colours you already chose on the Appearance tab. It shows on your storefront; the editor's preview doesn't draw it.