WhatsApp is the world's most-used messaging app, recognized instantly by its bright green speech-bubble logo and the blue double-check that means "read." The design philosophy is radical restraint: cream backgrounds, green outgoing bubbles, white incoming bubbles, system fonts, and almost nothing else. The chrome disappears so two billion conversations can be the interface.

This system captures that calm-utility DNA — the iconic doodle-pattern wallpaper tone, the signaling green, the whisper-light shadows, and the rounded message-bubble geometry that feels native on every platform from Lagos to São Paulo.