<===> input.scss
@-moz-keyframes animatetoptop /* Firefox */ line 429
{
from {width:0%}
to {width:100%}
}
<===> output.css
@-moz-keyframes animatetoptop /* Firefox */ line 429 {
  from {
    width: 0%;
  }
  to {
    width: 100%;
  }
}