index.css

html {
  font-family: Helvetica Neue, Helvetica, Arial;
}

button {
  font-size: 24px;
  padding: 10px;
  margin: 20px 5px;
}

@media (max-width: 700px) {
  h1 {
    font-size: 18px;
  }
  h4 {
    font-size: 14px;
  }
  label {
    font-size: 12px;
  }
  button {
    font-size: 18px;
  }
  #kirby {
    max-height: 60px;
  }
}