There are a ton of things you can do with CSS animations. If you need something to run infinitely, it allows for that easily.
Example
<div class="my-container">
<div class="my-box"></div>
</div>
* {
box-sizing: border-box;
}
.my-container {
position: relative;
height: 300px;
border: 10px solid;
}
.my-box {
position: absolute;
padding: 10px;
border: 2px solid;
width: 50px;
height: 50px;
animation: diagonal infinite 3s alternate linear;
}
@keyframes diagonal {
0% {
top: 0;
left: 0;
}
100% {
top: calc(100% - 50px);
left: calc(100% - 50px);
}
}