cleaner.js

const fs = require('fs');

var unused = fs.readFileSync('./unused', 'utf-8').split('\n');
var src = fs.readFileSync('./bootstrap.css', 'utf-8');

function escapeString(string) {
	return string.replace(/[\(\)\[\]\\\.\^\$\|\?\+\*\{\}]/g, '\\$&');
}

unused.forEach(function(unusedRule) {
	if (!unusedRule) {
		return;
	};

	unusedRule = escapeString(unusedRule).replace(/\s/g, '\\s+');
	var ruleRegExp = new RegExp('}\\s+(' + unusedRule + '\\s*{[^}]*})', 'm');

	src = src.replace(ruleRegExp, function(a, b, c) {
		return '}';
	});
});
fs.writeFileSync('./bootstrap.clean.css', src, 'utf-8');