JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="interactive-background"> 
    <center>
      <a href='#01'> occupied link</a>
      <br />
      <a href='#02'> occupied link</a>
    </center>
  </div>
  <div class="controls">
    <div class="main-controls">
      <br />
    </div>
    <div class="actual-controls">
      <a href='#04'>toolbox link</a><br />
      <a href='#05'>toolbox link</a><br />
    </div>
  </div>
</div>

CSS

div.container {
    position: relative;
    height: 100%;
    width: 500px;
}

div.interactive-background {
    position: absolute;
    z-index: 0;
    background-color: rgba(255, 0, 0, 1);
    width: 100%;
    margin: 10px;
    padding: 10px;
}

div.controls {
    pointer-events: none;
    position: absolute;
    z-index: 10;
    background-color: rgba(0, 255, 0, 0.25);
    display: flex;
    width: 100%;
}

div.actual-controls {
    pointer-events: auto;
    background-color: rgba(0, 0, 255, 0.25);
    flex: 0 1 auto;
}

div.main-controls {
    flex: 1 0 0%;
    background-color: rgba(255, 255, 0, 0.25);
    width: 100%;    
    margin: 10px;
    padding: 10px;
}