components/Blue.js

import React from 'react';
import './Blue.css';

const Blue = () => {
  return <div className="Blue">Blue</div>;
};

export default Blue;

---

 

components/Blue.css

.Blue {
  background: blue;
  font-size: 1.5rem;
  color: white;
  width: 128px;
  height: 128px;
  display: flex;
  align-items: center;
  justify-content: center;
}

---