PENCIL is Brainly's design system, unusually broad in scope: beyond product components and grid guidelines, it covers branding and marketing templates for presentations, social media, events, and even swag.
It's strongest in demonstrating a genuinely holistic design system, one that treats brand and marketing assets as first-class citizens alongside product UI, rather than keeping those in a separate, disconnected brand book.
Design system leads arguing internally for a system that unifies product and marketing assets under one source of truth, not merely component libraries.
Guidelines are explicitly open for anyone at the company to use for any design task, worth studying as a model for internal adoption, not merely visual style.
Brainly's own design system, built to keep its learning platform experience consistent.