JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parent">
  <div class="title"></div>
  <div class="list">
    <div class="fixed-child"></div>
    <div class="resized-child"></div>
  </div>
</div>

CSS

.parent {
  height: 300px;
  width: 200px;
  display: flex;
  flex-direction: column;
  border: 2px solid black;
}

.title {
  height: 50px;
  flex: 0 0 auto;
  background-color: green;
}

.list {
  flex: 1 1 auto;
  background-color: red;
  border: 2px solid red;
}

.fixed-child {
  height: 50px;
  flex: 0 0 auto;
  background-color: blue;
}

.resized-child {
  flex: 1 1 auto;
  background-color: yellow;
  border-color: 1px solid yellow;
}