What color should the border background be for the number displayed on the robot?

The border background color for the number displayed on the robot should adhere to the requirement of being either the alliance color or a contrasting color. This ensures that the number is easily identifiable during matches, thus enhancing visibility for referees and spectators alike. By using the alliance color, teams can create a cohesive look that ties them to their alliance members, while a contrasting color can help differentiate the team number from the robot’s primary coloration, ensuring clarity during the competition.

Choosing any neutral color, matching the robot's color, or disregarding color entirely would not support the need for clear identification in the fast-paced environment of a robotics competition. For effective communication of team identities, specifically adhering to the guidelines regarding alliance colors and contrast is crucial for maintaining a well-organized competition.