wow, that's amazing! I'm gobsmacked you can make something like this with CSS, that is so cool
Rubber is a hard thing to get right imo, I was trying to paint it for one of the brush thumbnails of a rubber stamp (https://www.mediafire.com/view/46tten5kkzh2i99/Stamp_Diamond...) - and it was really difficult, I still don't think I got it quite right xD So I can't imagine how tough it would have been to try and create that texture using only CSS and JS back then