fathom/assets/js/components/login.js

import React, { Component } from 'react'

class Login extends React.Component {
  constructor(props) {
    super(props);
  }

  render() {

    return (
      <div className="block">
        <h2>Login</h2>
        <p>
          <a href="">Sign in</a>
        </p>
      </div>
    );
  }
}

export default Login