styles.css

@keyframes skew-x-shake {
 0% { transform: skewX(-15deg); }
 5% { transform: skewX(15deg); }
 10% { transform: skewX(-15deg); }
 15% { transform: skewX(15deg); }
 20% { transform: skewX(0deg); }
 100% { transform: skewX(0deg); }
}

span.skew-shake-x {
  animation: skew-x-shake 1.3s infinite;
}