button[type=submit] {
  &.ff-loading {
    display: inline-flex;
    flex-wrap: nowrap;
    align-items: center;

    &:before {
      content: '';
      display: block;
      flex: 1 0 11px;

      width: 11px;
      height: 11px;
      margin-right: 10px;

      border-style: solid;
      border-width: 2px;
      border-color: transparent transparent white white;
      border-radius: 50%;
      animation: ff-loading .5s linear infinite;
    }
  }
}

@keyframes ff-loading {
  0% {
    transform: rotate(0);
  }
  100% {
    transform: rotate(1turn);
  }
}