JSFiddle - React, Tailwind, and code Playground

HTML

<body>
<div class="fixed-top">
      <ul>
         menu content ....
      </ul>
      <div class="fixed-right">
        <ul>
           menu content .....
        </ul>
      </div>   
</div>
 <div class="main-content">
      </div>
</body>

CSS

.fixed-menu{ 
  position:fixed; 
  z-index: 1030; 
  top: 0; 
  left: 0; 
  background: red;
  height: 80px;
  width: 100%; 
  }
.fixed-right{
 position: fixed;
 z-index: -1;
 background: green;
 width: 280px;
 right: 0;
 left: auto;
 top: 0;
 bottom: 0;
      }