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>
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>
bootstrap justify-centre de contenu pour md
<div class="row justify-content-md-center"></div>
justifier-contenu-entre bootstrap 4
<div class="d-flex justify-content-start">...</div>
<div class="d-flex justify-content-end">...</div>
<div class="d-flex justify-content-center">...</div>
<div class="d-flex justify-content-between">...</div>
<div class="d-flex justify-content-around">...</div>
justifier l'espace de contenu entre le bootstrap de classe
<div class="row d-flex justify-content-between"></div>
bootstrap justify-centre de contenu pour lg
<div class="row justify-content-lg-center"><div>