PHP Fatal error: Call-time pass-by-reference has been removed in includes/acp/acp_styles.php on line 482
and several similar errors when using PHP 5.4

@return documentation is invalid

There is a lot of extra spacing where it shouldn't be

Global variables should not be used in functions other than main()

usort should use array($this, 'sort_styles') instead of 'acp_styles::sort_styles'