CSS Animation rotate3d not working in Safari - html

Question

I cannot get this animation to work in Safari 12 no matter what I try. I've tried vendor prefixes and all, but nothing works.
It works fine in Chrome. Anyone have any ideas?
<div class="spinners"></div>
This is the css:
#keyframes spinx {
0% {
transform: rotate3d(0, 1, 1, 360deg);
}
100% {
transform: rotate3d(0, 0, 0, 360deg);
}
}
.spinners {
display: block;
width: 100%;
height: 4rem;
overflow: hidden;
position: relative;
}
.spinners:before, .spinners:after {
content: "";
width: 4rem;
height: 4rem;
border: 3px solid red;
border-radius: 50%;
position: absolute;
top: 50%;
left: 50%;
margin: -2rem 0 0 -2rem;
display: block;
transform-origin: 50% 50% 0;
}
.spinners:before {
animation: spinx 2s infinite linear;
}
.spinners:after {
border-color: blue;
animation: spinx 4s infinite linear alternate;
}
Here's a demo:
https://codepen.io/Skinner927/pen/vVEdag

Answer 1

Seems like both Safari and Firefox don't recognise the change between the two key frames. To solve this you can use an intermediate keyframe:
50% {
transform: rotate3d(0, 1, 1, 180deg);
}
Demo:
#keyframes spinx {
0% {
transform: rotate3d(0, 1, 1, 360deg);
}
50% {
transform: rotate3d(0, 1, 1, 180deg);
}
100% {
transform: rotate3d(0, 0, 0, 0);
}
}
.spinners {
display: block;
width: 100%;
height: 4rem;
overflow: hidden;
position: relative;
}
.spinners:before,
.spinners:after {
content: "";
width: 4rem;
height: 4rem;
border: 3px solid red;
border-radius: 50%;
position: absolute;
top: 50%;
left: 50%;
margin: -2rem 0 0 -2rem;
display: block;
transform-origin: 50% 50% 0;
}
.spinners:before {
animation: spinx 2s infinite linear;
}
.spinners:after {
border-color: blue;
animation: spinx 4s infinite linear alternate;
}
<div class="box">
<div class="spinners"></div>
</div>