CSS3 Spin Animation

You have implemented the animation styles correctly, but your animation isn't working because you haven't defined keyframes for the animation.

CSS3 animations require keyframes to define the start and end states of the animation.

To fix the issue, add keyframes to your CSS code. This will define how your element will transform during the animation. Here's an example of how to do it:

@keyframes spin {
  from {
    transform: rotate(0deg);
  }
  to {
    transform: rotate(360deg);
  }
}

This defines a keyframe that starts the animation at 0 degrees and ends it at 360 degrees. You can customize these values to create the desired animation effect.

Here's a demo to illustrate the solution:

div {
  margin: 20px;
  width: 100px;
  height: 100px;
  background: #f00;
  animation-name: spin;
  animation-duration: 4000ms;
  animation-iteration-count: infinite;
  animation-timing-function: linear;
}
@keyframes spin {
  from {
    transform: rotate(0deg);
  }
  to {
    transform: rotate(360deg);
  }
}

With these changes, your element should now spin continuously. Remember, for CSS3 animations to work, you need to define both the animation styles and the animation keyframes.