body {
  margin: auto;
  max-width: 40em;
  font-family: "Serif";
  font-size: 150%;
}

img {
  width: 100%;
  max-width: 40em;
}

code,
pre {
  background-color: #000000;
  border-radius: 0.25em;
  border-style: none;
  color: #ddddff;
  font-family: monospace;
  font-weight: bold;
}

pre {
  border-color: #8080ff;
  border-radius: 1em;
  border-style: outset;
  border-width: 0.25em;
  padding: 0.5em;
}

nav {
  background-color: #8080ff;
  color: #ffffff;
  padding: 0 0.25em 0 0.25em;
  position: fixed;
  width: 100%;
  left: 0px;
  top: 0px;
}

nav>a:link {
  color: #ffffff;
}

nav>a:visited {
  color: #ffffff;
}

a:focus {
  background-color: #cccc44;
}

a {
  color: #007bff;
  text-decoration: none;
  transition: color 0.3s ease;
}

a:hover {
  color: #004085;
}

h1 {
  text-align:center;
  text-decoration: underline #8080ff double;
}