PHPファイルのスタイルをCSSスタイルシートに変換する方法

preg_match_all("/<style type=\"text\/css\">(.*?)<\/style>/s", $phpcontent, $styles);

$cssrules = array();
foreach ($styles[1] as $style) {
    preg_match_all('/([\w\s.#{}:,%_-]*)\{([^\}]*)\}/', $style, $matches, PREG_SET_ORDER);
    foreach ($matches as $match) {
        $selectors = preg_split('/,\s*/', $match[1], -1, PREG_SPLIT_NO_EMPTY);
        $props = preg_split('/;\s*/', $match[2], -1, PREG_SPLIT_NO_EMPTY);
        foreach ($selectors as $selector) {
            $selector = trim($selector);
            if(!isset($cssrules[$selector])) {
                $cssrules[$selector] = array();
            }
            foreach ($props as $prop) {
                list($prop, $value) = explode(':', $prop);
                $cssrules[$selector][trim($prop)] = trim($value);
            }
        }
    }
}

$cssfile = 'style.css';
file_put_contents($cssfile, '');
foreach ($cssrules as $selector => $props) {
    $line = $selector . " {\n";
    foreach ($props as $prop => $value) {
        $line .= "\t" . $prop . ': ' . $value . ";\n";
    }
    $line .= "}\n";
    file_put_contents($cssfile, $line, FILE_APPEND);
}