topLevel.js

var postcss = require('postcss');

module.exports = function(css) {
  var root = postcss.parse(css);

  // 1. Parse the AST and collect all font-size declarations
  var properties = findFontSizeDecl(root);

  // 2. Calculate the ratio used and the quality of the fit
  var results = calculateRatio(properties);
  
  console.log(results);
};