Datatables export: Html formatting a messageBottom info

actually i use DT in a project and i need to export the generated table info in PDF and since here everything is fine. Another need for me is to add additional info possibly at the bottom of the table (not in footer or in header) and the only alternative seems to be the

messageBottom: "MY ADDITIONAL INFO GOES HERE",

As the info i need to insert are numbers and an explanation i need to format this info for example using different styles (principally just different font size). I read a lot of documentation, i found some examples here on SO but still i cant figure out the desired result. Any help will be highly appreciated.

examples and documentation:

https://datatables.net/extensions/buttons/examples/html5/titleMessage.html

DataTables exporting PDF/Excel with footnotes here i try using push but still html formating dont work.

this is my code i use actually:

messageBottom: "\n\nALL INFO: 
   InitValue: ( '.$result_info_footer["vl_init"].' ) + 
   [ Total A ( '.$result_info_footer["total_A"].' ) - 
     Tot B ( '.$result_info_footer["total_B"].' ) 
   ] = 
  '.$result_info_footer["final_total"].' USD.",

And the final result, when i export in pdf is the table and below the table this message:

ALL INFO: InitValue: (100.00) + [ Total A (20.00) - Total B (11.00) ] = 109.00 USD

And i want that: 109.00 USD to be formatted in bold or with a bigger font size.

Hope my explanation is clear, in case of doubts just ask please.

ps:

'.$result_info_footer["vl_init"].'
'.$result_info_footer["total_A"].'
'.$result_info_footer["total_B"].'
'.$result_info_footer["final_total"].'

these are php values returned from query as this script is running on server side and the table is generated from php file.