在Selenium [Python]中使用PhantomJS的透明屏幕截图?

When I take a screenshot in with PhantomJS as the webdriver in Selenium, all I get is a transparent background. Any clue why? It works with pages such as Google.com, but not kahoot.it, the one I want. It also works with everything else I need in Firefox, but not in PhantomJS.When I take a screenshot in with PhantomJS as t