Assets and Static Files
Use assets for theme files and static for files that should be copied as-is.
Leaf supports two kinds of non-content files.
Theme assets live under the active theme:
themes/default/assets/css/style.css
themes/default/assets/js/app.js
Theme static files are copied as-is:
themes/default/static/robots.txt
themes/default/static/favicon.ico
Site-level static files can also live in:
static/
Use assets for CSS and JavaScript that belong to the theme. Use static files for things that should appear in the output exactly as they are.
It is not glamorous. It is useful. Useful wins a lot.