@hjr265, While solving any problem we can easily see it’s language factors by clicking on the Limits. There is a close (x) button too for closing the factor chart. But in a contest problem, there is no close button. That’s why we can’t close it. So if we press back (for going into the previous page) there shows a dark layer. We’ve to refresh the page for removing the dark layer. Please add a close button in contest problem’s language factors chart too.
[Please note that my device is a Smartphone]