body {
  background-color: #f0f8ff;
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
}

header, footer {
  background-color: #e0e0e0;
  padding: 1em;
  text-align: center;
}

nav ul {
  list-style: none;
  padding: 0;
}

nav li {
  display: inline;
  margin: 0 10px;
}

main {
  padding: 1em;
}

section {
  margin-bottom: 1em;
}

aside {
  background-color: #fffbe6;
  padding: 1em;
  border-left: 4px solid #ffd700;
  margin-top: 1em;
}