Sass function to generate a stack of paper, influenced by this article https://css-tricks.com/snippets/css/stack-of-paper/#comment-1612614, written on Sass Meister https://www.sassmeister.com/gist/d01e53698b7fdc9a151729e4d9bd62c8

SassMeister-input-HTML.html

 <div class="paper">
    Howdy
</div>

SassMeister-input.scss

// ----
// Sass (v3.4.21)
// Compass (v1.0.3)
// ----

//box-shadow: [horizontal offset] [vertical offset] [blur radius] [optional spread radius] [color];

@function paperShadow($depth) {
  $val:  0 -1px 1px rgba(0,0,0,0.15);
  @for $i from 1 through $depth {
    $v-offset: 10 * $i; 
    $spread-radius-layer: $v-offset /2; 
    $spread-radius-shadow: $spread-radius-layer - 1;
    //Create new layer
    $val: #{$val} , 0  -#{$v-offset}px 0 -#{$spread-radius-layer}px #eee ;
    //Create shadow for layer
    $val: #{$val} , 0  -#{$v-offset}px 1px -#{$spread-radius-shadow}px rgba(0,0,0,0.15);
  }
  @return $val;
}

.paper {
  background: #fff;
  box-shadow:paperShadow(2);
    /* Padding for demo purposes */
    padding: 50px;
}

body {
  background-color: #333;
  padding: 5em;
}

SassMeister-output.css

.paper {
  background: #fff;
  box-shadow: 0 -1px 1px rgba(0, 0, 0, 0.15), 0 -10px 0 -5px #eee, 0 -10px 1px -4px rgba(0, 0, 0, 0.15), 0 -20px 0 -10px #eee, 0 -20px 1px -9px rgba(0, 0, 0, 0.15);
  /* Padding for demo purposes */
  padding: 50px;
}

body {
  background-color: #333;
  padding: 5em;
}

SassMeister-rendered.html

 <div class="paper">
    Howdy
</div>