body {
  font-family: sans-serif;
  margin: 0;
  padding: 0;
  background: #fefefe;
  color: #333;
}
header, footer {
  background: #f4f4f4;
  padding: 1em;
  text-align: center;
}
main {
  padding: 1em;
}
#gallery img {
  width: 150px;
  height: auto;
  margin: 0.5em;
  border-radius: 4px;
}
.download-button {
  display: inline-block;
  margin-top: 1em;
  padding: 0.5em 1em;
  background: #0077cc;
  color: white;
  text-decoration: none;
  border-radius: 5px;
}