In this project, we're going to use styled-component (https://www.styled-components.com/). It is one of the most popular libraries discussed on the internet. It allows CSS inside the JS components. You can learn more about how it can be used from the documentation website.

To give an example, an HTML div component can be created as follows:

const AppWrapper = styled.div`
  max-width: calc(768px + 16px * 2);
  margin: 0 auto;
  display: flex;
  min-height: 100%;
  padding: 0 16px;
  flex-direction: column;
  .btn {
    line-height: 0;
  }
`;