<div class="box">
  <img src="https://images.unsplash.com/photo-1534361960057-19889db9621e?ixid=MXwxMjA3fDB8MHxzZWFyY2h8Mjh8fGRvZ3xlbnwwfHwwfA%3D%3D&ixlib=rb-1.2.1&auto=format&fit=crop&w=1000&q=60" alt="강아지" />  
</div>
img {
  width: 300px;
  display: block;
}

.box {
  width: 100%;
  height: 500px;
  background: #d8f3dc;
  display: flex;
  justify-content: center;
  align-items: center;
}

External CSS

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External JavaScript

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