How to add style to parent div when children divs have specific className

Question

In mu angular project, I have simple divs like

<div class="parent">
    <div class="child1">
        div1
    </div>
    <div class="child2 green">
        div2
    </div>
</div>

.green {
  background-color:green
}

You could see that div2 has background color green(it is added dynamically from a third-party plugin), how could I write scss code to make the div1 also shows green when div2 has the class 'green', is it possile?