There seems to be no documentation and I don't quite understand the code examples on the Github page.
I assumed that it would automatically append reset rules to the output CSS file. The documentation uses things like
The syntax you are talking about (
__) is just a CSS methodology called BEM (Block - Element - Modifier) trying to keep CSS maintainable. There is no more hidden magic to it. Further info: http://getbem.com/
postcss-autoreset plugin basically just adds the
all: initial; property to selectors, which might already have some styles. Therefore you can be sure of no other styles conflicting with your CSS.