This small repo demonstrates a proper file structure for a Flask app. The folders named static and templates are required.
Routes and static files are handled correctly in all src and href attributes in the template files.
The template file base.html is used as a shell by the other three HTML templates. This means they insert content into base.html according to Jinja2 template rules.
After installing all dependencies, run the app by entering its folder and typing:
$ python routes.py