reactintro_style.jsx

render() {
  const { firstNameError, firstName } = this.state;

  return (
    <div
        style={{
          margin: 50,
          padding: 10,
          width: 300,
          border: "1px solid black",
          backgroundColor: "black",
          color: "white"
        }}
      >
      <div style={{marginBottom: 10}}>
        <label>
          First name:
          <input
            style={{backgroundColor: '#EFEFFF', marginLeft: 10}}
            type="text"
            name="firstName"
            onChange={this.onFirstNameChange}
            onBlur={this.onFirstNameBlur}
          />
          {firstNameError && <div style={{color: 'red', margin: 5}}>{firstNameError}</div>}
        </label>
      </div>

      <Greetings
        firstName={firstName}
      />
    </div>
  );
}