# Themes

In MycorrhizaWiki, themes are used to specify what is shown to a user, the front-end. So, a theme consists of:

- **HTML templates.** Data is inserted into them.
- **CSS.**
- **JS.**

Your HTML template structure must be identical to the one. You can include any CSS and JS in your themes.

See [default-light](/:sys/theme/default-light) theme for more information. This is the only theme that is guaranteed to work.