Зміна кольору

<div class="color-shift">
  <div class="color-shift__blob"></div>
</div>

<style>
.color-shift {
  position: relative;
  width: 200px;
  height: 140px;
  border-radius: 18px;
  background: #0b1120;
  border: 1px solid rgba(255, 255, 255, 0.2);
  overflow: hidden;
}

.color-shift__blob {
  position: absolute;
  inset: -20% auto auto -20%;
  width: 80%;
  height: 140%;
  background: conic-gradient(from 90deg, #3b82f6, #8b5cf6, #22d3ee, #3b82f6);
  animation: hueSpin 6s linear infinite;
  opacity: 0.7;
}

@keyframes hueSpin {
  to {
    transform: rotate(360deg);
  }
}
</style>