5.11 CSS Modules And Media Queries

Person.js

.Person {
  width: 60%;
  margin: 16px auto;
  border: 1px solid #eee;
  box-shadow: 0 2px 3px #ccc;
  padding: 16px;
  text-align: center;
}

@media (min-width: 500px) {
  .Person {
    width: 450px;
  }
}

App.js

...

  render() {
    let persons = null;
    let btnClass = "";

    if (this.state.showPersons) {
      persons = (
        <div>
          {this.state.persons.map((person, index) => {
            return (
              <Person
                click={() => this.deletePersonHandler(index)}
                name={person.name}
                age={person.age}
                key={person.id}
                changed={(event) => this.nameChangedHandler(event, person.id)}
              />
            );
          })}
        </div>
      );

      btnClass = classes.Red;
    }

    const assignedClasses = [];
    if (this.state.persons.length <= 2) {
      assignedClasses.push(classes.red); // classes = ['red']
    }
    if (this.state.persons.length <= 1) {
      assignedClasses.push(classes.bold); // classes = ['red', 'bold']
    }

    return (
      <div className={classes.App}>
        <h1>Hi, I'm a React app!</h1>
        <p className={assignedClasses.join(" ")}>This is really working!</p>
        <button className={btnClass} onClick={this.togglePersonsHandler}>
          Toggle Persons
        </button>
        {persons}
      </div>
    );
  }
}

export default App;