.manual-slide1 {
  position: relative;
}
.manual-slide1 img {
  position: absolute;
  padding: 0;
  width: 420px;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  opacity: 0;
  animation : slideshow1 10s linear infinite;
}
@keyframes slideshow1 {
  0%   { opacity: 0; }
  28%  { opacity: 1; }
  50%  { opacity: 1; }
  75%  { opacity: 0; }
  100% { opacity: 0; }
}