$re = '/([^a-z0-9\)\];\-_]*\{)/i';
$str = 'a {
color:black;
background-color:blue;
}
{color:red}
<!-- TEST -->
@media screen and (max-width:620px) {
/* TEST 2 */
a.test {color:blue;}
p[class="test2"] {color:green;}
}';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php