They copied strings, and visual design. Both of which are work, both of which are covered by copyright.

Designs and strings are only sometimes covered under copyright.

The elements of a design that are ornamental, utilitarian, or a general look and feel are not covered under copyright but would be covered under a design patent if one exists.

Strings are only covered under copyright if they are a sufficiently original work of human expression. Simple informational messages generally wouldn't qualify.