html {
  width: 100%;
  height: 100%;
  color: black;
  font-family: Roboto, sans-serif;
}
article {
  flex-grow: 1;
}
body {
  width: 100%;
  height: 100%;
  max-width: 600px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
}
header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin: 1.75rem 0;
  padding: 0.25rem 0;
  height: 3rem;
}
header h1 {
  font-size: 1.5rem;
  padding: 0;
}
header h1 a {
  background: yellow;
  text-decoration: none;
  color: black;
  padding: 0.5rem;
}
footer {
  color: rgb(77, 81, 86);
  padding: 1rem;
  padding-right: 2rem;
  align-self: end;
  font-size: 0.75rem;
}
nav {
  display: flex;
  align-items: end;
}
nav li {
  display: inline;
  margin-left: 0.75rem;
}
nav li:last-of-type {
  margin-right: 2rem;
}
nav li a {
  padding: 0.5rem;
  text-decoration: none;
  color: black;
}
nav li a:hover {
  background: rgba(0, 0, 0, 0.1);
}
strong {
  font-weight: bold;
}
h1 {
  font-size: 2rem;
  padding: 1rem 0;
}
h2 {
  font-size: 1.5rem;
  padding: 2rem 0 1rem;
}
h3 {
  font-weight: bold;
  padding: 1rem 0 1rem;
}
p {
  color: #333;
  line-height: 1.5rem;
  padding-top: 1.5rem;
}
em {
  font-style: italic;
}
mark {
  background: #f9f;
  padding: 0.25rem;
}
ul {
  list-style: disc;
}
li {
  line-height: 1.5rem;
  margin-left: 1rem;
}
input {
  appearance: none;
  font-family: inherit;
  font-size: 100%;
  margin: 0;
  box-sizing: border-box;
  height: 30px;
  border: 1px solid black;
}

@media screen and (max-width: 600px) {
  header {
    flex-direction: column;
    justify-content: space-between;
    align-items: flex-start;
    height: 5rem;
    margin-left: 2rem;
  }
  article {
    margin-left: 2rem;
    margin-right: 2rem;
  }
  header h1 {
    height: 3rem;
    margin-bottom: 1rem;
  }
  nav li {
    display: block;
    margin: 0.5rem;
    margin-left: 0;
  }
  nav li a {
    padding-left: 0;
  }
}