Beginner question - custom css

[Jake-Jasper]

Why is my custom css not working?

I have a directory

/datasette-testing:
   /static
      -test.css
   /templates
      /pages
         - about.html
   metadata.json
   my.db

run using datasette datasette-testing/

I have just copied the https://github.com/simonw/datasette/blob/main/datasette/static/app.css as my "test.css" but have changed the colour of the footer from background-color: #276890; to background-color: #000000;

However, my "custom" CSS is not being loaded. What am I doing wrong?

[Jake-Jasper]

Never mind, have found the answer to my own question>
I needed to add:

 "extra_css_urls": [
        "/static/test.css"]

to the metadata.json file