title: Unable to locate elements on webpage with headless chrome
body: <p>I have a script that's accessing printers, and my code works totally fine when chrome is run normally, but when it's run headless, selenium can't seem to find elements on the webpage.</p>
  
  <p>Here's the relevant code:</p>
  
  <p>init method:</p>
  
  <pre><code>def __init__(self, ip_address):
      """ Initialize a new Printer_Webpage object."""
      self.ip_address = ip_address
      chrome_options = Options()
      chrome_options.add_argument("--headless")
      chrome_options.add_argument("--disable-gpu")
      chrome_options.add_argument("--window-size=1920x1080")
      self.browser = webdriver.Chrome(chrome_options=chrome_options)
      # Ignore lack of cert for each printer web page.
      # Otherwise, can't open page.
      self.browser.accept_untrusted_certs = True
  </code></pre>
  
  <p>Login method:</p>
  
  <pre><code>def login(self):
      """Navigates through the login page for the printer."""
      # Open login page
      self.browser.get(f'https://{self.ip_address}/wcd/top.xml')
      # STEPS TO LOGIN:
      # 1) Select 'Administrator' radio button and click.
      self.browser.find_element_by_id('Admin').click()
      # 2) Select Login button and click.
      self.browser.find_element_by_xpath("//input[@type='submit' \
                                          and @value='Login']").click()
      # 3) Select admin (user mode)
      self.browser.find_element_by_id('R_ADM2').click()
      # 4) Select password field and input PASSWORD, then submit.
      password_field = self.browser.find_element_by_id('Admin_Pass')
      password_field.send_keys(PASSWORD)
      password_field.send_keys(Keys.RETURN)
  </code></pre>
  
  <p>Full error message:</p>
  
  <pre><code>selenium.common.exceptions.NoSuchElementException: Message: no such element: Unable to locate element: {"method":"id","selector":"Admin"}
  </code></pre>
  
  <p>And here's some other info that might be of use:</p>
  
  <pre><code>(Session info: headless chrome=62.0.3202.94)
  
  (Driver info: chromedriver=2.33.506120 (e3e53437346286c0bc2d2dc9aa4915ba81d9023f),platform=Windows NT 10.0.14393 x86_64)
  </code></pre>