body {
  min-width: 300px;
}

header,
footer {
  margin: 0;
  padding: 0;
}

main {
  margin: 0 $gutter;
  padding: 0;
}

@media screen and (min-width: 426px) {
  footer,
  main {
    margin: 0 auto;
    width: 425px;
  }
}

@media screen and (min-width: 768px) {
  footer,
  main {
    width: calc(100% * 0.809);
    max-width: 860px;
  }
}