What is pelle-d-umore?

Pelle d'Umore is a small front-end toolkit that lets an AI chat assistant change how a whole chat interface looks and feels, not just what it says. Most chat interfaces show every message in the same flat style no matter what emotion the words carry. This project gives the AI persona a way to reach past the plain text and affect the room around it, so a phrase can glow, the whole screen can shift to a corrupted red mood, or the background can open into a starry night sky. It works through two kinds of effects. Inline text effects are tags the AI writes directly into its message, like glow, whisper, shake, or glitch, which get turned into styled spans of text. Full-screen mood skins are a separate, bigger switch: the AI includes a hidden tag like mood rage or mood moonlight in its reply, and the whole page re-skins under a single data attribute, changing colors, adding effects like static or a starfield, until the mood is turned off again. The flow is: the model writes a hidden mood tag in its reply, the server strips that tag out before showing the text to the user and sends a small separate event describing the mood, the client-side code applies that mood by setting an attribute on the page body, and a CSS file swaps the visual theme based on that attribute. Removing the attribute instantly restores the user's own normal theme with nothing left behind. The project ships as four dependency-free files (two CSS files, a JavaScript module, and a small script), plus a demo page and a suggested prompt block to paste into an AI system prompt to teach it the available tags. It also respects a user's reduced-motion accessibility setting, turning off animation while keeping color changes, and pauses effects when the browser tab is hidden. This project came out of a private AI companion app and was released as a separate, reusable tool for anyone building a chat interface who wants their AI persona to have a more expressive presence than plain text alone.