* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html, body {
  width: 100%;
  height: 100%;
  overflow: hidden;
}

.gallery {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  overflow: hidden;
}

.gallery-img {
  position: absolute;
  width: 100vw;
  height: 100vh;
  object-fit: cover; /* allow cropping, no distortion */
  opacity: 0;
  transition: opacity 0.5s ease-in-out;
}

.gallery-img.show {
  opacity: 1;
  z-index: 2;
}

.nav-button {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  font-size: 3rem;
  color: white;
  background-color: rgba(0, 0, 0, 0.3);
  padding: 0.5rem;
  cursor: pointer;
  z-index: 10;
  user-select: none;
  border-radius: 5px;
  transition: background 0.3s;
}

.nav-button:hover {
  background-color: rgba(0, 0, 0, 0.6);
}

.nav-button.left {
  left: 10px;
}

.nav-button.right {
  right: 10px;
}