<div class="container">
  <div class="pool">
    <div class="fixed"></div>
  </div>
</div>
.container {
  position: relative;
  height: 800px;
  width: 100%;
  overflow-y: scroll;
}
.pool {
  --s: 50px; /* control the size */
  --c1: #81d4fa;
  --c2: #E1F5FE;
  

  --_g: calc(2 * var(--s)) calc(2 * var(--s))
    radial-gradient(25% 25%, var(--c1) 99%, #0000 101%);
  background: 0 var(--s) / var(--_g), var(--s) 0 / var(--_g),
    radial-gradient(50% 50%, var(--c2) 97%, #0000) calc(var(--s) / 2)
      calc(var(--s) / 2) / var(--s) var(--s),
    linear-gradient(90deg, var(--c1) 50%, var(--c2) 0) 0 0 / calc(2 * var(--s));

  height: 300vh;
  width: 100%;
  position: relative;
}

.fixed {
  position: fixed;
  top: 60px;
  left: 60px;
  height: 100px;
  width: 100px;
  background-image: url("https://cdn-icons-png.flaticon.com/512/1239/1239062.png");
  background-size: 100px;
    
}
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