Just pointing this out, every webpage that works in Safari 10 on Sierra should work in Leopard-WebKit. Just note that if you go to the
main project page on SourceForge, the main download button is for an older version. However, as of right now it says the last update was 6 days ago. Go to "Files" and locate the newest version there. Then it should work with every website you can throw at it. Thanks
@Hack5190! He's the one to share this with me.