CodePen

HTML

            
              <div class="parent">
  <div class="child">
    Sup<br/>
    Sup<br/>
    Sup<br/>
    Sup<br/>
    Sup<br/>
    Sup<br/>
    Sup<br/>
    Sup<br/>
    Sup<br/>
  </div>
</div>

<div class="parent">
  <div class="child">
    Sup<br/>
    Sup<br/>
  </div>
</div>

<h1>This header is not entirely visible because we've got some overflow issues.</h1>
            
          
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CSS

            
              *
{
  -moz-box-sizing: border-box;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
}

.parent
{
  display: inline-block;
  position: relative;
  width: 31em;
  height:100px;
  padding: 5px;
  background:#000;
}

.child
{
  color:#FFF;
  position: absolute;
  min-height: 100%;
  min-height: calc(100% - 10px);
  top: 5px;
  left:5px;
  right: 5px;
  padding:10px;
  background: red;
}
            
          
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JS

            
              
            
          
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