function _twig_escape_css_callback($matches) {
$char = $matches[0];
// \xHH
if (!isset($char[1])) {
$hex = ltrim(strtoupper(bin2hex($char)), '0');
if (0 === strlen($hex)) {
$hex = '0';
}
return '\\' . $hex . ' ';
}
// \uHHHH
$char = twig_convert_encoding($char, 'UTF-16BE', 'UTF-8');
return '\\' . ltrim(strtoupper(bin2hex($char)), '0') . ' ';
}