We maintain a design portal at [https://design.home-assistant.io](https://design.home-assistant.io) that provides information about various frontend aspects such as:
When new components or features are added to the frontend, those need to be added to the design portal. This portal page explains the details on how to do so: [https://design.home-assistant.io/#design.home-assistant.io/editing](https://design.home-assistant.io/#design.home-assistant.io/editing)
While the portal is publically named "design", it is referred to as "gallery" in the frontend repository. That is why the script to run the gallery locally in your development environment can be found at `gallery/script/develop_gallery` and the source code in `gallery/src`.