button:hover { animation: sparkle 1.2s ease-in-out infinite; box-shadow: 0 0 5px purple, 0 0 25px purple; } @keyframes sparkle { 0% 100% {transform: scale(1); box-shadow: 0 0 10px purple;} 50% {transform: scale(1.05); box-shadow: 0 0 25px purple;} }