Definitely just speculating here, but there is a `driver.save_screenshot(path)` method that would probably be worth trying.
This worked for me:
from selenium.webdriver import Firefox
from selenium.webdriver.firefox.options import Options
geckodriver_path = '/usr/local/bin/geckodriver'
options = Options()
options.add_argument('-headless')
driver = Firefox(executable_path=geckodriver_path, firefox_options=options)
url='https://news.ycombinator.com/item?id=16576015'
driver.get(url)
driver.save_screenshot('./hn.png')
