body {
  margin: 0;
  font-family: sans-serif;
}

header,main {
  width: 100%;
  margin: 0 auto;
  padding: 1rem 2rem;
  box-sizing: border-box;
}
@media (min-width: 768px) {
  header,  main {
    width: 50%;  
  }
}

header {
  display: flex;
  justify-content: flex-end;
}

.nav-link {
  text-decoration: none;
  color: black;
}

pre code {
  display: block;
  overflow-x: auto;
}

code {
  font-family: monospace;
}

img {
  display: block;
  max-width: 100%;
  height: auto;
  margin: 0 auto;
}