<style>
    .box-with-hole {
        height: 200px;
        width: 200px;
        background-color: green;
        -webkit-mask: url('data:image/svg+xml;utf8, \
            <svg viewBox="0 0 200 200" version="1.1" xmlns="http://www.w3.org/2000/svg"> \
                <rect width="100%" height="100%" fill="white"/> \
                <rect x="25%" y="25%" width="50%" height="50%" fill="black"/> \
            </svg>') luminance no-repeat;
    }
</style>
<body>
    <div class="box-with-hole"></div>
</body>