JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="first-child">
      Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua
  </div>
  <div class="second-child">
      Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua
  </div>
</div>

SCSS

.container {
  display: flex;
  flex-direction: column;
  width: 150px;
  height: 200px;
  background-color: #A5D6A7;
  
  .first-child {    
    flex: 1 1 auto;     
    min-height: 0; 
    
    width: 125px;
    box-sizing: border-box;
    overflow: auto;
    background-color: #90CAF9;  }
  
  .second-child {
    flex: 0 0 75px;    

    width: 125px;
    box-sizing: border-box;
    overflow: auto;
    background-color: #CE93D8;
  }
}