add style to group row names datatable

avb

I use the row grouping datatable plugin. On the following script i have a background color for each new rows of the group according to the name of the group .

That s not what i want, I would like to add a background color directly on the row of the group. ex : when the group name "Cardio-training" is deteted, i would like to add a background color on it. ( see on the attached image )

Have you got an idea? thank you

here is the javascript/jquery script :

api.column(3, {page:'current'} ).data().each( function ( group, i ) {
       if ( last !== group ) {
           $(rows).eq( i ).before(
               '<tr><td class="espace" colspan="5"></td></tr>',
               '<tr class="group"><td colspan="5">'+group+'</td></tr>'
           );

           last = group;
       }                

   } );  

     "createdRow" : function (tr, tdsContent) {
      if (tdsContent[3] === 'Cardio-training' {
      tr.style.backgroundColor='red'; }}