body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  background: #f5f5f5;
}
header nav {
  background: #003366;
  color: #fff;
  display: flex;
  justify-content: space-between;
  padding: 1em;
}
header nav a {
  color: #fff;
  text-decoration: none;
  margin: 0 1em;
}
.card {
  background: #fff;
  border-radius: 8px;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
  padding: 1em;
  margin: 1em;
}
.button {
  display: inline-block;
  padding: 0.5em 1em;
  background: #003366;
  color: #fff;
  border-radius: 4px;
  text-decoration: none;
}
footer {
  text-align: center;
  padding: 1em;
  background: #003366;
  color: #fff;
}