Also, you have typos: animation-fill-mode: forwads;
This is one of the many reasons I do not do any editing inside the codepen editor. I suggest you edit your code in something like Visual Studio Code. If you want to be able to see your changes live, then there are packages for that (I use live-server). It is as easy as typing in the cmd:
> npm install live-server
Let that finish
> live-server .
It will automatically open a local network and your browser on your current workspace.