alinhar os itens com a barra de inicialização Central
<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 4 à direita
<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>
justify-content-center do MD
<div class="row justify-content-md-center"></div>
justify-content-between 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>
justificar o espaço de conteúdo entre a classe bootstrap
<div class="row d-flex justify-content-between"></div>
justify-content-center para lg
<div class="row justify-content-lg-center"><div>