JSFiddle - React, Tailwind, and code Playground

HTML

<div class="block1">
  <div class="block2">
  </div>
  <div class="block3">
    <div class="block4">
    
    </div>
  </div>
</div>

CSS

.block1 {
  height: 200px;
  width: 100%;
  background: gray;
}

.block2 {
  height: 50px;
  width: 100%;
  background: red;
}

.block3 {
  /* как сделать красивый height без calc?*/
  height: calc(100% - 50px);
  width: 100%;
  background: yellow;
  overflow-y: auto;
}

.block4 {
  height: 9999999px;
  background: green;
  width: 100%:
}