Or, until you turn off CSS (firefox: View->Page Style->No Style).
Then all the text appears, even without any JS running.
Then all the text appears, even without any JS running.
Save the page to disk (Firefox: File->Save Page As).
Then open the saved html file in a text editor and delete all of the <link> tags in the <head> section that reference style sheets and save the changes.
Then open the edited html page from disk, and the result will be printable.