body {
  max-width: 640px;
  margin: 0 0 0 auto;
  padding: 8px;
  font-family: sans-serif;
}

ul {
  list-style-type: none;
}

header ul {
  padding-inline-start: 50px;
  margin-block: 30px;
}

header li {
  margin: 20px 0;
}

main details {
  padding: 30px 10px;
}

main li {
  clear: both;
  text-align: right;
}

main li b {
  float: left;
  padding-right: 2ch
}

img {
  margin: 10px auto;
  max-width: 100%;
}

summary a, footer a {
  float: right
}

mark {
  color: #f66;
  background: none;
}

hr {
  clear: both
}

footer a {
  padding-bottom: 30vh;
}

@media (prefers-color-scheme: dark) {
  body { background: #000; color: #eee }
  a { color: #ccf }
  mark { color: #fcc }
  hr { border-color: #555 }
}