Corrupted JPEG

<!-- Corrupted JPEG — a few macroblock-colored tiles briefly jitter into
     view once per 5s cycle (a single short burst, not a repeating strobe),
     then vanish, mimicking a compression-error frame. -->
<div class="nuda-gd2-jpeg-corrupt">
  <span>IMG_042</span>
  <span class="nuda-gd2-jpeg-corrupt__block" aria-hidden="true"></span>
  <span class="nuda-gd2-jpeg-corrupt__block" aria-hidden="true"></span>
  <span class="nuda-gd2-jpeg-corrupt__block" aria-hidden="true"></span>
  <span class="nuda-gd2-jpeg-corrupt__block" aria-hidden="true"></span>
</div>

.nuda-gd2-jpeg-corrupt {
  position: relative;
  display: grid;
  place-items: center;
  width: 160px;
  aspect-ratio: 4/3;
  border-radius: 10px;
  overflow: hidden;
  background: linear-gradient(135deg,#121216,#09090b);
  color: #e4ff54;
  font: 800 1rem/1 ui-monospace,SFMono-Regular,Menlo,monospace;
  letter-spacing: .08em;
}

.nuda-gd2-jpeg-corrupt__block {
  position: absolute;
  width: 22%;
  height: 18%;
  opacity: 0;
  animation: _nuda-gd2jpeg-corrupt 5s steps(1) infinite;
}

.nuda-gd2-jpeg-corrupt__block:nth-of-type(1) {
  top: 20%;
  left: 10%;
  background: rgba(0,229,255,.32);
  animation-delay: .3s;
}

.nuda-gd2-jpeg-corrupt__block:nth-of-type(2) {
  top: 55%;
  left: 60%;
  background: rgba(255,0,212,.3);
  animation-delay: .6s;
}

.nuda-gd2-jpeg-corrupt__block:nth-of-type(3) {
  top: 65%;
  left: 15%;
  background: rgba(228,255,84,.28);
  animation-delay: .15s;
}

.nuda-gd2-jpeg-corrupt__block:nth-of-type(4) {
  top: 10%;
  left: 65%;
  background: rgba(0,229,255,.25);
  animation-delay: .45s;
}

@keyframes _nuda-gd2jpeg-corrupt {
  0%,90%,100% {
    opacity: 0;
    transform: translate(0,0);
  }
  92% {
    opacity: 1;
    transform: translate(3px,0);
  }
  94% {
    opacity: 1;
    transform: translate(-3px,2px);
  }
  96% {
    opacity: 1;
    transform: translate(2px,-2px);
  }
  98% {
    opacity: 0;
    transform: translate(0,0);
  }
}

@media (prefers-reduced-motion:reduce) {
  .nuda-gd2-jpeg-corrupt__block {
    animation: none;
    opacity: 0;
  }
}