html,
body {
  height: 100%;
}

body {
  font-family: Helvetica, Arial, sans-serif;
  margin: 0;
  line-height: 1.3;
  display: flex;
  flex-direction: column;
}

main,
header,
footer {
  margin: 2rem;
}

@media screen and (min-width: 500px) {

  main,
  header,
  footer {
    max-width: 40rem;
  }
}

main {
  flex: 1;
}

main img {
  max-width: 100%;
}

header {
  margin-bottom: 0;
}

header h1 {
  margin: 0;
}

header + main {
  margin-top: 1rem;
}

h1,
h2,
h3 {
  line-height: 1.1;
}

h1 a {
  color: inherit;
  text-decoration: none;
}

ul li {
  margin-top: 0.5rem;
  margin-bottom: 0.5rem;
}

table {
  border-collapse: collapse;
  text-align: left;
}

td,
th {
  border: 1px solid #ddd;
  padding: 0.25rem 0.5rem;
}

.flex-column {
  display: flex;
  flex-direction: column;
}