"Install the extension" is a link bringing you to the chrome web store, where you can install it by clicking in the upper-right. The link is this, in case it's Github giving you trouble somehow.
If the Chrome web store isn't recognizing that you're running Chrome, that's probably not a thing I can fix, though you could try saving this link as something.user.js, opening chrome://extensions, and dragging the file onto the window.
Thank you. That worked. I never would have guessed that an icon which simply had the word "free" on it was the download button.
Would it be worth your while to do this for LW? It makes me crazy that the purple edges for new comments are irretrievably lost if the page is downloaded again.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one.
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.