<!DOCTYPE html>
<html lang="en">
<head>
<style>
    .container {
        width: 200px;
        height: 200px;
        border: 1px solid black;
    }
    .clipped {
        width: 180px;
        height: 180px;
        margin: 10px;
        background-color: green;
        -webkit-clip-path: url(#clipper);
    }
</style>
</head>
<body>

<div class="container">
    <div class="clipped box"></div>
</div>

<svg height="0">
    <clipPath id="clipper" clipPathUnits="objectBoundingBox">
        <rect x="0.25" y="0.25" width="0.5" height="0.5"/>
    </clipPath>
</svg>

</body>
</html>