<div class="page-scroll-item">
  <div class="scroll-wrapper-1">
    <div class="scroll-wrapper-2">
      <div class="scroll-item-2">
      </div>
    </div>
    <div class="scroll-item-1">
    </div>
  </div>
.page-scroll-item {
  height: 200vh;
}
.scroll-wrapper-1 {
  display: flex;
  height: 200px;
  width: 80vw;
  overflow-y: scroll;
}
.scroll-wrapper-2 {
  height: 100px;
  width: 60vw;
  overflow-y: scroll;
}
.scroll-item-2 {
  height: 800px;
  background-image: linear-gradient(to top, #a18cd1 0%, #fbc2eb 100%);
}
.scroll-item-1 {
  height: 800px;
  background: #aaa;
  flex: 1;
}

External CSS

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External JavaScript

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