Starting today 10/16/17, HackerRank will not support fullscreen mode for candidates attempting the test using IE 11 or Safari. We recommend that whenever you send a invite for a test with fullscreen enabled, please add instructions for candidates to use latest version of Chrome, Firefox or Microsoft Edge to take the test.
Note, we will continue to support IE 11 and Safari browsers. This update only impacts candidates using IE 11 or Safari when the test specifically has fullscreen mode enabled.
If you have any questions, please refer to this article or write to us at support@hackerrank.com.