body {
  margin: 0;
  font-family: 'Poppins', Arial, sans-serif;
  line-height: 1.6;
}

/* HEADER */
header {
  background: #0A3D62;
  color: white;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 15px 40px;
}

nav a {
  color: white;
  margin-left: 15px;
  text-decoration: none;
}

/* HERO (đã gộp + fix full) */
.hero {
  background: url("https://images.unsplash.com/photo-1586528116311-ad8dd3c8310d") center/cover;
  color: white;
  text-align: center;

  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;

  padding: 120px 20px;
}

.hero h2 {
  font-size: 48px;
}

/* BUTTON */
.btn {
  display: inline-block;
  background: #ff6a00;
  color: white;
  padding: 12px 25px;
  margin-top: 20px;
  text-decoration: none;
  border-radius: 5px;
}

/* SECTION */
.section {
  padding: 60px 40px;
  max-width: 1100px;
  margin: auto;
}

/* DARK SECTION */
.dark {
  background: #0A3D62;
  color: white;
}

/* GRID */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px,1fr));
  gap: 20px;
}

/* CARD */
.card {
  border: 1px solid #ddd;
  padding: 20px;
  border-radius: 8px;
  background: white;
  transition: 0.3s;
}

.card:hover {
  transform: translateY(-8px);
  box-shadow: 0 10px 25px rgba(0,0,0,0.15);
}

/* FOOTER */
footer {
  background: #0A3D62;
  color: white;
  text-align: center;
  padding: 20px;
}

/* MOBILE RESPONSIVE */
@media (max-width: 768px) {

  header {
    flex-direction: column;
    text-align: center;
  }

  .hero {
    padding: 80px 15px;
  }

  .hero h2 {
    font-size: 28px;
  }

  .section {
    padding: 40px 20px;
  }

}