Compress CSS

if ( ! function_exists( 'polygon_compress_internal_stylesheet' ) ) {
    /**
     * Compress dynamic stylesheet.
     *
     * Compress the internal stylesheet by stripping all comments, spaces and empty lines.
     * The function also places everything on the same line in order to make the source code
     * easy to scan.
     *
     * @since  1.0.0
     * @param  string $buffer Stylesheet generated by the options from the customizer.
     * @return string         The compressed stylesheet stored in $buffer.
     */
    function polygon_compress_internal_stylesheet( $buffer ) {
        // Remove comments.
        $buffer = preg_replace( '!/\*[^*]*\*+([^/][^*]*\*+)*/!', '', $buffer );
        // Remove space before bracket.
        $buffer = str_replace( ' {', '{', $buffer );
        // Remove space after colons.
        $buffer = str_replace( ': ', ':', $buffer );
        // Remove tabs, spaces, newlines, etc.
        $buffer = str_replace( array( "\r\n", "\r", "\n", "\t", '  ', '   ', '    ' ), '', $buffer );
        return $buffer;
    }
}