How do I center a Bootstrap Card Image [duplicate]

问题

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How to center cards in bootstrap 4? (2 answers)

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Closed 2 years ago.

How do I center an image in a Bootstrap 4 card? It's a vertical image and it looks wrong being left-aligned. I've been reading the Bootstrap Card documentation and can't find anything about centering the image.

<div class="card-deck">
  <div class="card col-sm-3">
    <div>
      <img class="card-img-top" src="image_URL" alt="alt-text" >
      <div class="card-block">
        <div class="card-text">
            text
        </div>
      </div>
    </div>
  </div>

来源：https://stackoverflow.com/questions/44914373/how-do-i-center-a-bootstrap-card-image