But does it mean the 15% is non-standard or just not implemented at all? If it’s not implemented then all of the implementation is 100% standard compliant and if everyone stopped relying on the 15% part then developing for Firefox should make it compatible for rest of the browsers.
I’ve heard of it too. You would need an analytical balance to get accurate measurements weighing a piece of paper. Just cut out the part you want to take an integral of, then cut out a piece of paper with known size (or cut several pieces with different sizes to get more accurate results) and weigh each of them. I guess this used to be cheaper and faster than using computers when computers were big and expensive.
Can you give an example how that would happen?