/* General Page */
body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: #f3f4f6;
  color: #111827;
  margin: 0;
  padding: 0 20px;
}

/* Top Navigation */
.top-nav {
  background: #1d4ed8;
  padding: 10px 20px;
}

.top-nav .nav-link {
  color: white;
  text-decoration: none;
  font-weight: bold;
}

.top-nav .nav-link:hover {
  text-decoration: underline;
}

/* Header */
header {
  text-align: center;
  margin: 30px 0;
  background: linear-gradient(90deg, #3b82f6, #2563eb);
  color: white;
  padding: 30px 20px;
  border-radius: 16px;
}

header h1 {
  font-size: 2.5rem;
  margin-bottom: 10px;
}

header p {
  font-size: 1.2rem;
}

/* Sections */
.section {
  margin-bottom: 50px;
}

/* Buttons */
button {
  padding: 12px 25px;
  margin: 10px;
  border: none;
  border-radius: 12px;
  font-weight: bold;
  cursor: pointer;
  transition: transform 0.2s, background-color 0.2s;
  color: white;
  background-color: #3b82f6;
}

button:hover,
button:focus {
  transform: translateY(-2px);
  background-color: #2563eb;
  outline: none;
}

button.secondary {
  background-color: #6b7280;
}

button.secondary:hover {
  background-color: #4b5563;
}

button.danger {
  background-color: #ef4444;
}

button.danger:hover {
  background-color: #b91c1c;
}

/* Cards */
.cards-demo {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
}

.card {
  flex: 1 1 200px;
  background: #fff;
  padding: 20px;
  border-radius: 16px;
  box-shadow: 0 4px 6px rgba(0,0,0,0.1);
  cursor: pointer;
  transition: transform 0.3s, box-shadow 0.3s;
}

.card:hover,
.card:focus {
  transform: translateY(-5px);
  box-shadow: 0 8px 20px rgba(0,0,0,0.2);
  outline: none;
}

/* Modal */
.modal {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.6);
  display: flex;
  justify-content: center;
  align-items: center;
}

.modal-content {
  background: #fff;
  padding: 30px;
  border-radius: 20px;
  width: 90%;
  max-width: 400px;
  box-shadow: 0 12px 24px rgba(0,0,0,0.3);
  transition: transform 0.3s;
}

.hidden {
  display: none;
}

/* Responsive */
@media (max-width: 768px) {
  .cards-demo {
    flex-direction: column;
  }

  header h1 {
    font-size: 2rem;
  }
}