JSFiddle - React, Tailwind, and code Playground

HTML

<div class="A">
  <div class="B">
  </div>
</div>

CSS

*{
    margin:0;
    padding:0;
}


.A {
  background-color: blue;
  height: 200px;
  position:relative;
}

.B {
    margin-left: 2%;
    margin-top:5%;
    padding-bottom:2%;
    width:7.4%;
    background-color: red;
    position:absolute;

}