A plugin for Rainbow to show linenumbers.
Just include Rainbow.linenumbers.js alongside Rainbow.js
The text color of the numbers is that of the <pre> tag. The line color is that of the border-color of the <pre> tag. To start at a specific line number include the attribute data-line="123" in your <code> tag.
Make sure the word-wrap of your <code> tag is set to normal (this plugin is not build for wrapping single lines).