.subject {

  background: repeating-linear-gradient(

    0deg,

    red,

    red 5px,

    white 5px,

    white 10px

  );

  width: 200px;

  height: 200px;

}

​

.backdrop {

  height: 200px;

  -webkit-backdrop-filter: blur(50px);

  backdrop-filter: blur(50px);

  margin: 10px;

  animation: wiggle 10s infinite;

  border: 1px solid #aaa;

}

​

@keyframes wiggle {

  0% { transform: translateY(0); }

  10% { transform: translateY(30px); }

  30% { transform: translateY(-30px); }

  60% { transform: translateY(90px); }

  80% { transform: translateY(-90px); }

  100% { transform: translateY(0); }

}