.container {
  display: grid;
  grid-template-columns: 1fr 3fr;
  grid-template-rows: auto auto; <-- second row (where 'aside' is placed) is
                                     set to content-based height
  grid-template-areas: 'nav nav ' 'aside main';
  height: 100%;
}

.main-container {
  display: grid;
  grid-template-columns: 1fr 3fr;
  grid-template-rows: auto auto; <-- second row (where 'bottomright' is placed) is
                                     also set to content-based height
  grid-template-areas: 'topleft topright' 'bottomleft bottomright';
  height: 100%;
}