Flexbox and Bootstrap

index.html

<div class="row">
  <div class="col-3 offset-2 bootstrap-ex">
    <h1 class="text-center">Bootstrap</h1>
  </div>
</div>

<div class="flexbox-ex">
  <div class="flexbox-ex-inner">                                        
    <h1>Flexbox</h1>
  </div>
</div>

style.scss

.row {                                                                  
  margin-top:20px;                                                      
  border-style:solid;                                                   
  border-color:black;                                                   
}                                                                       
                                                                        
.bootstrap-ex {                                                         
  border-style:solid;                                                   
  border-color:black;                                                   
  height:80px;                                                          
  margin-top:20px;                                                      
  margin-bottom:20px;                                                   
}                                                                       
                                                                        
.flexbox-ex-inner {                                                     
  display:flex;                                                         
  border-style:solid;                                                   
  border-color:black;                                                   
  margin-top:20px;                                                      
  margin-bottom:20px;                                                   
  margin-left: 300px;                                                   
}                                                                       
                                                                        
.flexbox-ex {                                                           
  margin-top: 20px;                                                     
  display:flex;                                                         
  border-style:solid;                                                   
  border-color:black;                                                   
}