<div class="box"></div>
body{
  height:100vh;
  background:yellowgreen;
}
.box{
  width:100px;
  height:100px;
  border:3px solid rgba(255,0,0,.5);
  box-shadow:10px 5px 0 0 rgba(0,0,0,.5);
  background:transparent;
}

External CSS

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External JavaScript

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