@media (max-width: 1024px) {
  nav {
    width: 10em
  }
}

@media (max-width: 1024px) {
  #listing.list .item.header,
  main {
    width: calc(100% - 13em)
  }
}

@media (max-width: 736px) {
  nav {
    top: 0;
    z-index: 9999;
    background: #fff;
    height: 100%;
    width: 13em;
    box-shadow: 0 0 5px rgba(0, 0, 0, 0.1);
  }

  #listing.list .item.header, main {
    width: calc(100% - 2em);
  }

  main {
    margin: 0 1em;
    width: calc(100% - 2em);
  }
}