CodePen

HTML

            
              <header></header>
<div class="content"></div>
            
          
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CSS

            
              header {
  height:150px;
  background:green;
}

.content {
  width:960px;
  margin:-50px auto 0 auto;
  min-height:150px;
  background:lightgreen;
}
            
          
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JS

            
              
            
          
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