How to fix HTML in repeating function ACF

first of all I´m a beginner in coding, I wrote this function to show ACF repeater timleine And he returns the result to me, but a problem when I add html

function wpb_nos_formules(){
$html = '';
if( have_rows('formule') ) : 
    $html .='<section class="design-process-section" id="process-tab">
    <div class="container">
    <div class="row">
    <div class="col-xs-12">';
    while( have_rows('formule') ) : the_row(); 
    $title = get_sub_field("title");
    $html .='<ul class="nav nav-tabs process-model more-icon-preocess" role="tablist">
                 <li role="presentation" class="active"><a href="" aria-controls="discover" role="tab" data-toggle="tab"><i class="fa fa-search" aria-hidden="true"></i>
                 <p>'.$title.'</p></a></li>
            </ul>';
    if( have_rows('slider') ) :
        $html .='<div class="tab-content">';
        while( have_rows('slider') ) : the_row(); 
        $titlee      = get_sub_field("title");
        $description = get_sub_field("description"); 
        $html .='
        <div role="tabpanel" class="tab-pane active" id="">
        <div class="design-process-content">
          <h3 class="semi-bold">'.$titlee.'</h3>
         <p>'.$description.'</p>
         </div>
      </div>';
    endwhile; endif;
    $html .='</div>'; 
    endwhile; endif;
    $html .='</div></div></div></section>'; 
 return $html;
}
add_shortcode( 'latest_nos_formule', 'wpb_nos_formules' );

first problem check this picture the result what i want

source https://stackoverflow.com/questions/67781071/how-to-fix-html-in-repeating-function-acf