#videos-container {
    display: flex;
    width: 200%;
    animation: float-horizontal 5s linear infinite;
    overflow: hidden;
}

.iframe-container {
  position: relative;
  width: 100%;
  overflow: hidden;
  margin-right: 5px;
  padding-top: 28.1%; 
}

.placeholder {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  z-index: 1;
  cursor: pointer;
  opacity: 1;
  transition: opacity 3.0s ease-in-out;
}

.responsive-iframe {
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  right: 0;
  width: 100%;
  height: 100%;
  border: none;
  z-index: 0;
  opacity: 0;
  transition: opacity 3.0s ease-in-out;
}

@keyframes float-horizontal {
  0% {
    transform: translateX(0);
  }
  100% {
    transform: translateX(-1000px);
  }
}