<html>
<head>
<style>
.square {
  margin: 25px;
  height: 200px;
  width: 200px;
  background-color: black;
  border-radius: 100px;
}

#negative {
  position: absolute;
  top:  10px;
  left: 10px;

  -webkit-box-shadow: inset  40px 0px 0px -10px #00f,
                      inset  80px 0px 0px -15px #808, 
                      inset 120px 0px 0px -20px #b04,
                      inset 160px 0px 0px -25px #f00;
}

#positive {
  position: absolute;
  top:   10px;
  left: 300px;

  -webkit-box-shadow: inset  40px 0px 0px  10px #00f,
                      inset  80px 0px 0px  15px #808, 
                      inset 120px 0px 0px  20px #b04,
                      inset 160px 0px 0px  25px #f00;
}

#mixed1 {
  position: absolute;
  top:  300px;
  left:  10px;

  -webkit-box-shadow: inset  40px 0px 0px  10px #00f,
                      inset  80px 0px 0px -15px #808, 
                      inset 120px 0px 0px  20px #b04,
                      inset 160px 0px 0px -25px #f00;
}

#mixed2 {
  position: absolute;
  top:  300px;
  left: 300px;

  -webkit-box-shadow: inset  40px 0px 0px -10px #00f,
                      inset  80px 0px 0px  15px #808, 
                      inset 120px 0px 0px -20px #b04,
                      inset 160px 0px 0px  25px #f00;
}

</style>
<script>
if (window.testRunner)
    testRunner.dumpAsText(true);
</script>
</head>
<body>
<p>Bug <a href="https://bugs.webkit.org/show_bug.cgi?id=51386">51386</a></p>
<div class="square" id="negative"></div>
<div class="square" id="positive"></div>
<div class="square" id="mixed1"></div>
<div class="square" id="mixed2"></div>
</body>
</html>