foreach ( explode( "\n", $diff_str ) as $line ) {
        if ( 0x2d == ord( $line ) ) {
            $diff_from_default4disp .= "<span style='color:var(--color-red);'>" . $line . "</span>\n";
        } elseif ( 0x2b == ord( $line ) ) {
            $diff_from_default4disp .= "<span style='color:var(--color-blue);'>" . $line . "</span>\n";