react-query/examples/react/playground/src/styles.css

body {
  margin: 0;
  padding: 1rem;
  font-family:
    -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen', 'Ubuntu',
    'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue', sans-serif;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  color: white;
  background: #0b1521;
}