tabular audit

Use an absolute path and use `os.path.join` to build paths.

Understand that the above variable (what you are calling `static_dir`) is meant to be the URI for the assets directory, **not** the directory itself. It is used to build the URIs that the user will include in `<link>` and `<script>` tags when they render their template.

However, the path that you pass to `os.listdir` is a filepath, and should therefore use the `os.path` module for building paths in a cross-platform way.