Solid Glass: a free design system for building AI agent interfaces

Solid Glass is an open-source design system from DeepLethe, made as a single stylesheet for shadcn/ui projects on React 19 and Tailwind CSS 4, so existing components pick up the look without code changes. Beyond the theme, it adds components made for apps where an AI agent works, such as a status line for what the agent is doing, a message box, the steps it took, a diff view, a question card, a context-usage ring and a reasoning panel. It comes in dark and light themes, is MIT licensed and passed 1,700 GitHub stars within a week of its 12 October release.