<!--
     Any copyright is dedicated to the Public Domain.
     http://creativecommons.org/licenses/publicdomain/
-->
<!DOCTYPE html>
<html>
<head>
<style>
.unit { display:inline-block; width:100px; height:1px; background:blue; }
</style>
</head>
<body style="margin:0; width:300px; line-height:100px;">
  <span class="unit"></span><span class="unit"
  ></span><span style="background:-moz-element(#g)"><span class="unit"></span><span class="unit"
  ></span></span>

  <svg>
    <linearGradient gradientUnits="userSpaceOnUse" id="g" x1="0" y1="0" x2="200" y2="0">
      <stop stop-color="lime" stop-opacity="0" offset="0"></stop>
      <stop stop-color="lime" stop-opacity="0" offset="0.5"></stop>
      <stop stop-color="lime" offset="0.5"></stop>
      <stop stop-color="lime" offset="1"></stop>
    </linearGradient>
  </svg>
</body>
</html>