* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  font-family: Arial, Helvetica, sans-serif;
}

body {
  background: #f4f4f4;
  color: #333;
}

header {
  background: #003366;
  color: #fff;
  text-align: center;
  padding: 25px 15px;
}

header h1 {
  margin-bottom: 5px;
}

main {
  padding: 20px;
}

.gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  gap: 15px;
}

.gallery img {
  width: 100%;
  height: 200px;
  object-fit: cover;
  border-radius: 6px;
  cursor: pointer;
  background: #ddd;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.gallery img:hover {
  transform: scale(1.05);
  box-shadow: 0 8px 20px rgba(0,0,0,0.25);
}

footer {
  background: #003366;
  color: #fff;
  text-align: center;
  padding: 12px;
  margin-top: 30px;
  font-size: 14px;
}

.gallery {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 12px;
}

@media (min-width: 768px) {
  .gallery {
    grid-template-columns: repeat(auto-fill, minmax(220px, 1fr));
  }
}

@media (min-width: 1200px) {
  .gallery {
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
  }
}

.lightbox {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.9);
  display: none;
  justify-content: center;
  align-items: center;
  z-index: 9999;
}

.lightbox img {
  max-width: 90%;
  max-height: 90%;
  border-radius: 6px;
}

.lightbox .close {
  position: absolute;
  top: 20px;
  right: 30px;
  font-size: 40px;
  color: #fff;
  cursor: pointer;
}

.lightbox .nav {
  position: absolute;
  top: 50%;
  font-size: 50px;
  color: #fff;
  cursor: pointer;
  user-select: none;
  padding: 10px;
}

.lightbox .prev { left: 20px; }
.lightbox .next { right: 20px; }

@media (max-width: 600px) {
  .lightbox .nav {
    font-size: 40px;
  }
}