body {
  font-family: Arial, sans-serif;
  margin: 0;
  background: #f2f2f2;
  color: #333;
}

header {
  background: #004466;
  color: white;
  padding: 20px;
  text-align: center;
}

nav a {
  color: white;
  margin: 0 15px;
  text-decoration: none;
}

.gallery {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
  padding: 20px;
}

.thumb {
  width: 200px;
  height: 150px;
  object-fit: cover;
  cursor: pointer;
  transition: transform 0.3s;
}

.thumb:hover {
  transform: scale(1.05);
}

.viewer {
  position: fixed;
  top: 0; left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0,0,0,0.9);
  display: none;
  justify-content: center;
  align-items: center;
  flex-direction: column;
}

.viewer img {
  max-width: 90%;
  max-height: 80%;
  margin-bottom: 20px;
}

.viewer button {
  background: white;
  border: none;
  font-size: 30px;
  margin: 0 20px;
  cursor: pointer;
  padding: 10px 20px;
  border-radius: 10px;
}

@media (max-width: 600px) {
  .thumb {
    width: 100px;
    height: 75px;
  }
}