demo-container {
display: block;
padding: 25px 10px 10px;
border-radius: 4px;
width: 200px;
height: 130px;
border: 1px solid rgb(128, 128, 128);
margin-bottom: 10px;
overflow: visible;
background-image: linear-gradient(transparent, transparent 49%, black 50%, black 51%, transparent 52%);
}

demo-object {
display: block;
background-color: rgb(255, 0, 0);
offset-path: path("M 20 65 L 160 65");
animation: 3000ms ease-in-out 0s infinite alternate none running move;
width: 20px;
height: 20px;
}
.element {offset-distance: 0%;}
@keyframes move {
0% { offset-distance: 0%; }
100% { offset-distance: 100%; }
}