.imsgbg {
  animation:slide 3s ease-in-out infinite alternate;
  background-image: linear-gradient(-60deg, #6c3 50%, #09f 50%);
  bottom:0;
  left:-50%;
  opacity:.5;
  right:-50%;
  top:0;
  position: static;
  z-index: 100;
}

.imsgbg2 {
  animation-direction:alternate-reverse;
  animation-duration:4s;
}

.imsgbg3 {
  animation-duration:5s;
}

.imsgbgcontent {
  background-color:rgba(255,255,255,.8);
  border-radius:.25em;
  box-shadow:0 0 .25em rgba(0,0,0,.25);
  box-sizing:border-box;
  left:50%;
  padding:10vmin;
  text-align:center;
  top:50%;
  transform:translate(-50%, -50%);
}

@keyframes slide {
  0% {
    transform:translateX(-25%);
  }
  100% {
    transform:translateX(25%);
  }
}