Reveal answers for {,image} lists, word fills and grids in senecalearning.com.
This is a simple css rule that shows answers for the following questions:
Download the repository, either with git or with the the 'code' button at the top of the page -> Download ZIP then extract it.
Go to chrome://extensions, enable developer mode then click 'Load unpacked' and find the unzipped directory.
Go to about:debugging -> This Firefox -> Load Temporary Add-on