.opening {
  box-sizing: border-box;
  max-width: 28rem;
  margin: 4rem auto;
  padding: 1.5rem;
  color: light-dark(#10261a, #f5efe2);
  background: light-dark(#faf4e8, #0a130d);
  border-radius: 1rem;
  font:
    1rem/1.5 system-ui,
    sans-serif;
}

.opening h1 {
  font-size: 1.5rem;
}