.btn-pixel-fx {
  background: #000;
  color: #fff;
  position: relative;
  overflow: hidden;
  border: none;
  padding: 12px 20px;
  font-weight: bold;
  transition: 0.3s ease;
}

.pixel-sparkle {
  position: absolute;
  width: 4px;
  height: 4px;
  background-color: #fff;
  animation: sparkle 1.5s infinite;
  opacity: 0;
}
.pixel-sparkle.p1 { top: 5px; left: 10px; animation-delay: 0s; }
.pixel-sparkle.p2 { top: 8px; left: 80%; animation-delay: 0.2s; }
.pixel-sparkle.p3 { top: 50%; left: 5px; animation-delay: 0.4s; }
.pixel-sparkle.p4 { bottom: 8px; left: 40%; animation-delay: 0.6s; }
.pixel-sparkle.p5 { bottom: 5px; right: 10px; animation-delay: 0.8s; }
.pixel-sparkle.p6 { top: 10px; right: 20px; animation-delay: 1s; }
.pixel-sparkle.p7 { bottom: 12px; left: 20%; animation-delay: 1.2s; }
.pixel-sparkle.p8 { top: 40%; right: 8px; animation-delay: 1.4s; }

@keyframes sparkle {
  0%, 100% { opacity: 0; transform: scale(0.8); }
  50% { opacity: 1; transform: scale(1.3); }
}