title: How to get css value of pseudo element with selenium python?
body: <p>I have html o page: </p>
  
  <pre><code>&lt;div id="foo" class="bar" title&gt;
    ::before
  &lt;/div&gt;
  </code></pre>
  
  <p>With Chrome or Firefox on selection <code>::before</code> I can see css on Styles tab:</p>
  
  <pre><code>.SomeTitle .bar::before{
  content: "required_value"
  }
  </code></pre>
  
  <p>After selection <code>&lt;div id="foo" class="bar" title&gt;</code> it presented in <code>Pseudo ::before element</code>. I did try to get value of <code>content</code>:</p>
  
  <pre><code>browser = webdriver.Firefox()
  browser.get(my_url)
  my_element = browser.find_element_by_xpath("//*[@id='foo']")
  my_elemet.value_of_css_property("content")
  </code></pre>
  
  <p>But it does returns none. How can I get value of <code>content</code>?</p>