Minify Kirby’s HTML output

minify-kirby.php

/**
 * Uses Alan Moore's regexp: 
 * http://stackoverflow.com/questions/5312349/minifying-final-html-output-using-regular-expressions-with-codeigniter
 *
 * Replace `echo $kirby->launch();` in Kirby’s index.php by
 * the following code to minify the HTML output
 * (it leaves whitespace within `<pre>` and `<textarea>` tags untouched)
 */
echo preg_replace(
    '/(?>[^\S ]\s*|\s{2,})(?=(?:(?:[^<]++|<(?!\/?(?:textarea|pre)\b))*+)
        (?:<(?>textarea|pre)\b|\z))/ix', '', $kirby->launch()
);