/* element selector */
body {
  font-family: Arial, Helvetica, sans-serif;
  line-height: 1.5;
  margin: 0;
  background-color: #f5f5f5;
}

/* id selector */
#page-header {
  background-color: #003366;
  color: white;
  padding: 1.5rem;
  text-align: center;
}

/* class selector */
.tagline {
  font-style: italic;
  margin-top: 0.5rem;
}

main {
  max-width: 900px;
  margin: 1.5rem auto;
  background: white;
  padding: 1.5rem;
  border-radius: 8px;
}

.topic-image {
  max-width: 100%;
  display: block;
  margin: 1rem 0;
}

h2 {
  color: #003366;
}

a {
  color: #0066cc;
}

footer {
  text-align: center;
  padding: 1rem;
  font-size: 0.9rem;
  color: #555;
}