This is a self Q&A of a handy piece of code I came up with.
Currently, there isn't an easy way to embed an SVG image and then have access to the SVG elements via CSS. There are various methods of using JS SVG frameworks, but they are overly complicated if all you are doing is making a simple icon with a rollover state.
So here is what I came up with, which I think is by far the easiest way to use SVG files on a website. It takes its concept from the early text-to-image replacement methods, but as far as I am aware has never been done for SVGs.
This is the question:
How do I embed an SVG and change its color in CSS without using a JS-SVG framework?