In the code below, I am creating a responsive 'rectangle' and 'square', along with making the text inside the p tag responsive.
#rectangle
{
display: flex;
width: 500px;
height: 150px;
background-color: brown;
}
#square
{
width: 300px;
height: 130px;
background-color: chocolate;
margin: 10px;
}
<div id="rectangle">
<div id="square">
</div>
<p>Lorem ipsum, dolor sit amet consectetur adipisicing elit. Aut, iusto. Sapiente fugiat illo
dolorum assumenda commodi!
</p>
</div>