$re = '/\b(border(?:-(?:top|bottom)-(?:left|right))?-radius)\s*:\s([^;]*)(?:;|$)/mi';
$str = 'border-radius: 5px;
Border-Radius: 5px 6px;
border-top-left-radius: 5px;
border-top-right-radius: 5px;
border-bottom-left-radius: 5px;
border-bottom-right-radius: 5px;
';
preg_match_all($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