<style>
.box { position: relative; width: 100px; height:100px; }
a { display: block; position: relative; width: 100px; height:100px; background-color: green; }
.background { background-color: green; }
.multiply { mix-blend-mode: multiply; }
</style>
<div>
    <div class="box background">
        <a class="multiply"></a>
    </div>
    <div class="box background">
        <a class="multiply"></a>
    </div>
    <div class="box background">
        <a class="multiply"></a>
    </div>
    <div class="box background">
        <a class="multiply"></a>
    </div>
    <div class="box background">
        <a class="multiply"></a>
    </div>
    <div class="box background">
        <a class="multiply"></a>
    </div>
</div>