Make diff-checker line change indicators (+ and -) into pseudo-elements to render them unselectable

Where looking at a file's diff, you can spot changes with the green/red background as well as the + and - signs at the start of the line. This is a nice feature, but it becomes a problem when you want to select and copy multiple lines: the indicators get copied as well.

My proposal is to get rid of these “hard-coded” indicators and replace them with a CSS pseudo-element so that they do not appear upon selection.

I have put together a script that you can use as a bookmarklet to test the idea out:
https://codepen.io/chrisknmojo/full/LwPgRG

It is a small enhancement that would make it easy to share code with colleagues, for instance, or to copy a few lines from one project to another very easily.

Let me know if this needs further clarification!

Thanks.