I just pushed out a change that makes it so that the markers change color when clicked in order to help you keep track of which ones you’ve seen. I haven’t tested it very heavily, but in my testing, it seemed to work as expected. Please let me know if it acts strangely (email@example.com).
I’d like to find some way to let them outlive the browser session, though. Currently, if you come back several days later, it’s likely that the ones you’ve seen will be back to red.