body {
  font-family: Arial, sans-serif;
  margin: 40px;
  background: #f8f9fa;
}
#calendar {
  max-width: 1000px;
  margin: auto;
  background: white;
  padding: 20px;
  border-radius: 12px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.1);
}
.btn-nav {
  border: none;
  background: #0d6efd;
  color: white;
  padding: 8px 16px;
  border-radius: 8px;
  cursor: pointer;
  margin: 0 5px;
}
.btn-nav:hover { background: #0b5ed7; }
.nav-container {
  text-align: center;
  margin-bottom: 10px;
}