index.css

body {
  margin: 0;
  padding: 0;
  font-size: 18px;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen,
    Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif;
}

h1 {
  font-size: 2rem;
}

h2 {
  font-size: 1.8rem;
}

h3 {
  font-size: 1.6rem;
}

h4 {
  font-size: 1.4rem;
}

h5 {
  font-size: 1.2rem;
}

h6 {
  font-size: 1rem;
}

.page-layout {
  margin: 2rem 0 0;
  display: grid;
  grid-template-columns: 1rem 1fr 1rem;
}

image-gallery,
.heading-section {
  grid-column: 2 / 3;
}

@media screen and (min-width: 40rem) {
  .page-layout {
    grid-template-columns: minmax(1rem, 1fr) minmax(0, 600px) minmax(0, 600px) minmax(
        1rem,
        1fr
      );
  }

  image-gallery {
    grid-column: 2 / 3;
  }

  .heading-section {
    grid-column: 3 / 4;
    padding: 1rem;
  }
}