Hackernews(https://news.ycombinator.com) comment/viewed improvements userscript.

• [21.] black font - unvisited story link, purple highlight - visited HN comments, red - 60 unseen comments.
• [22.] grey font - visited story link, green highlight - new HN story
• [23.] no highlight - unvisited HN comments
• [24.] black font - unvisited story link, green highlight - new HN story
• [25.] grey font - visited story link, purple highlight - visited HN comments, red - 8 unseen comments.

• red border/orange tint for new comments
• NEXT button in upper right corner jumps to the next new comment

Designed and tested on Chrome/Vivaldi/Opera using Tampermonkey. Uses localStorage to store "ID" = "highest ID, comments last seen" key/value pair.