artsite/test/styles.css

body {
  font-family: Arial, sans-serif;
  margin: 0;
}

.slideshow-container {
  position: relative;
  max-width: 1000px;
  margin: auto;
}

.mySlides {
  display: none;
}

.fade {
  animation-name: fade;
  animation-duration: 1.5s;
}

@keyframes fade {
  from {opacity: .4} 
  to {opacity: 1}
}