aligner les éléments centre bootstrap
<div class="d-flex align-items-start">...</div>
<div class="d-flex align-items-end">...</div>
<div class="d-flex align-items-center">...</div>
<div class="d-flex align-items-baseline">...</div>
<div class="d-flex align-items-stretch">...</div>
bootstrap flex wrap
<div class="d-flex flex-wrap">...</div>
boostrap droit alighn 4
<div class="float-left">Float left on all viewport sizes</div><br>
<div class="float-right">Float right on all viewport sizes</div><br>
<div class="float-none">Don't float on all viewport sizes</div>
flex d'affichage bootstrap
<div class="d-flex">I'm a flexbox container!</div>