Fatal error: margin in keyframes

[toptalo]

Using margins in animations is a bad idea, but this lines:

@keyframes example {
  0% {
    margin-left: 100px;
  }
  100% {
    margin-left: 0;
  }
}

returns:

[Lundefined:Cundefined]
>> ERROR: Fatal error, cannot continue: Cannot set property 'margin-left' of undefined undefined (undefined) Browsers: undefined