When configuring your Messages for Business experience, you can customize the colors of the conversation navigation bar and its back and Info buttons in iOS. These same colors appear in the message header in watchOS, brand name in watchOS, and recipient bubble in macOS.
Use sufficient color contrast ratios. Insufficient contrast makes content hard to see and can cause logos and buttons to blend in with the background. An online color contrast calculator can help you accurately analyze color contrast. Strive for a minimum contrast ratio of 4.5:1, although 7:1 is preferred because it meets more stringent accessibility standards. For guidance, see Color and effects.