Styling ranges of text in software is a very useful thing to be able to do. Thankfully, we have the CSS Custom Highlight API to look forward to because it represents the future of styling text ranges on the web.
One example: if you’ve ever used text editing software like Google Docs, Word, or Dropbox Paper, you’ll see they detect spelling and grammar errors and displaying nice little squiggly underlines below them to attract attention. Code editors like VS Code do the same for code errors.