How to add custom CSS file to Sphinx?

Issue

How can I add a custom CSS file? The following conf.py does not work:

html_static_path = ['_static']
html_theme = 'default'
html_theme_options = {
  'cssfiles': ['_static/style.css']
}

Result:

$ make html
Running Sphinx v1.2.2
loading pickled environment... not yet created
building [html]: targets for 2 source files that are out of date
updating environment: 2 added, 0 changed, 0 removed
reading sources... [ 50%] help
reading sources... [100%] index

looking for now-outdated files... none found
pickling environment... done
checking consistency... done
preparing documents...
Theme error:
unsupported theme option 'cssfiles' given

Solution

A simpler way is to add this to your conf.py:

def setup(app):
    app.add_css_file('css/custom.css')  # may also be an URL

Then put the file into the _static/css/ folder.

Answered By - Gringo Suave