body {
  background-color: #f5f5f5;
  color: #222;
  font-family: Arial, sans-serif;
  margin: 10px;
}

h1 {
  text-align: center;
}

nav {
  text-align: center;
  margin-bottom: 15px;
}

footer {
  text-align: center;
  margin-top: 20px;
}

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

figure {
  margin: 10px auto;
  max-width: 900px;
}

figcaption {
  text-align: center;
  margin-top: 8px;
}

audio {
  display: block;
  margin: 10px auto;
}

iframe {
  display: block;
  margin: 10px auto;
  max-width: 100%;
}