body {
  margin: 0;
  font-family: 'Segoe UI', sans-serif;
  background: linear-gradient(135deg, #004C97, #FFD700);
  color: #000;
}

/* Header-Bild */
.header-img {
  width: 100%;
  height: auto;
  max-height: 400px;
  object-fit: cover;
  display: block;
  border-bottom: 4px solid #FFD700;
}

/* Navigation */
.nav {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  padding: 1rem;
  background: rgba(255, 255, 255, 0.9);
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
  margin: 0;
  gap: 0.5rem;
}

.nav li {
  margin: 0.2rem 0.5rem;
}

.nav a {
  text-decoration: none;
  color: #004C97;
  font-weight: bold;
  padding: 0.5rem 1rem;
  border-radius: 8px;
  transition: all 0.3s ease;
}

.nav a:hover {
  color: #FFD700;
  background-color: rgba(0, 76, 151, 0.1);
}

/* Hauptbereich */
main {
  padding: 2rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

/* Bild im Main */
main img {
  max-width: 100%;
  height: auto;
  border-radius: 12px;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.2);
}

/* Buttons */
.book-container a {
  display: inline-block;
  padding: 1rem 2rem;
  background-color: #004C97;
  color: white;
  border-radius: 12px;
  text-decoration: none;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
  transition: background 0.3s, transform 0.2s;
}
.book-container a:hover {
  background-color: #003366;
  transform: translateY(-2px);
}

/* Responsive Anpassungen */
@media (max-width: 768px) {
  .nav {
    flex-direction: column;
    align-items: center;
  }
  .nav li {
    margin: 0.3re