@media (min-width: 900px) {
  body {
    display: grid;
    column-gap: 20px;
    grid-template: "a a a" auto
                   "b c c" / 1fr 1fr 1fr;
  }

  .wide-200px {
    width: 200px;
    height: 200px;
  }

  .wide-flex-row {
    display: flex;
    flex-direction: row;
    align-items: center;
  }
}

@media (max-width: 900px) {
  .narrow-full-width {
    width: 100%;
  }

  .narrow-hide {
    display: none;
  }
}

form {
  max-width: 50ch;
}

form input, form textarea {
  width: 100%;
}

p {
  margin: 15px;
}


.title {
  grid-area: a;
}

.nav {
  grid-area: b;
}

.main {
  grid-area: c;
}