hervorhebender, ungleicher Schatten unter einer Box

HTML

<div  class="content"><div class="gfg-root">
   CSS3-card-shadow - radial gradient
</div> </div>

CSS

.gfg-root { padding:10px; border:1px ridge #ccc;  }
.gfg-root {background:#fff}
.content { position:relative; width:50%;  margin-top:30px; z-index:0}
.content .shadow:after{
  
  bottom: -5px; 
  
  height: 8px;
  display: block;
  text-indent: -9999px;
  width: 100%;
  left:0;
  position: absolute;
  z-index:-1;

background-image: url(data:image/svg+xml;base64,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);0eT0iMSIvPgogIDwvcmFkaWFsR3JhZGllbnQ+CiAgPHJlY3QgeD0iLTUwIiB5PSItNTAiIHdpZHRoPSIxMDEiIGhlaWdodD0iMTAxIiBmaWxsPSJ1cmwoI2dyYWQtdWNnZy1nZW5lcmF0ZWQpIiAvPgo8L3N2Zz4=);
background-image: -ms-radial-gradient(center top, ellipse farthest-side, #aaaaaa 0%, #FFFFFF 100%);
background-image: -moz-radial-gradient(center top, ellipse farthest-side, #aaaaaa 0%, #FFFFFF 100%);
background-image: -o-radial-gradient(center top, ellipse farthest-side, #aaaaaa 0%, #FFFFFF 100%);
background-image: -webkit-gradient(radial, center top, 0, center top, 490, color-stop(0, #aaaaaa), color-stop(1, #FFFFFF));
background-image: -webkit-radial-gradient(center top, ellipse farthest-side, #aaaaaa 0%, #FFFFFF 100%);
background-image: radial-gradient(center top, ellipse farthest-side, #aaaaaa 0%, #FFFFFF 100%);

}

/* basics */
html {padding: 20px 0; background-color: #efefef;}
body {width: 80%; padding: 40px; margin: 0 auto; background: #fff; box-shadow: 1px 1px 5px rgba(0,0,0,0.5); font-family: Verdana, Arial,...