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HTML

            
              <h1>Placeholder selector extending a mixin</h1>

<div class="module">
<p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.</p>  
</div>
            
          
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↑ Insert the most common viewport meta tag

CSS

            
              @mixin box-emboss($outerOpacity, $innerOpacity) {
  box-shadow:
    rgba(white, $outerOpacity) 0 1px 0, 
    rgba(black, $innerOpacity) 0 1px 0 inset;
}
  
%box-emboss {
  @include box-emboss(0.7, 0.4);
}

header[role="banner"] {
  @extend %box-emboss;
}

.module {
  @extend %box-emboss;
  
  border-radius: 10px;
  background: #ccc;
  padding: 10px 20px;
}

body {
  padding: 10px 50px;
  background: #999;
}
            
          
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JS

            
              
            
          
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