JSFiddle - React, Tailwind, and code Playground

HTML

<div class="LeftContainerTop">
  <div class="SliderInContainerOnMainPage"></div>
</div>

CSS

.LeftContainerTop
{
  border: 1px solid green;
  flex-grow: 0.4;
  display: flex;
  align-items: center;
  justify-content: center;
  height:600px;
}

.SliderInContainerOnMainPage
{
  border: 1px solid red;
  flex-grow: 1;
 height:90%;
}