You must create themes in the /public/themes/
folder.
All themes must include an index.temlplate.php file to define the HTML structure of the theme.
You can seperate your theme on footer and header with help of chunks.
theme/ ├── css/ │ ├── theme.css ├── js/ ├── img/ ├── header.chunk.php ├── footer.chunk.php └── index.template.php
footer.chunk.php