I'm in a predicament with a specific issue. I am currently utilizing Angular to incorporate an Iframe. Let's imagine the angular app as A and the Iframe as B. B is being loaded within A. Within B, I have utilized CSS variables to define colors. In A, there is a color picker available. My goal is to apply the selected color from A's color picker onto the body of B. How can I go about changing the body color of B located inside an Iframe? To provide some context, think of WordPress's customize page. I aim to achieve something similar.