Как зафиксировать анимацию цсс?

*demo*/
.demo {
  border-top: 100px solid #ccc;
  height: 300px;
  font-family: sans-serif;
}
@keyframes grow {
    0% { position: absolute;
        left: -500px }
    100% { position: absolute;
        left: 0}
}
@-webkit-keyframes grow {
    0% { left: -500px }
    100% { left: 0}
}
.demo:hover .grows {
    animation-name: grow;
    animation-duration: 3s;
    -webkit-animation-name: grow;
    -webkit-animation-duration: 3s;
}
growsandstays {
    position: absolute;
    left: -500px;
}
.growsandstays {
    animation-name: grow;
    animation-duration: 3s;
    animation-fill-mode: forwards;
    -webkit-animation-name: grow;
    -webkit-animation-duration: 3s;
    -webkit-animation-fill-mode: forwards;
}