JSFiddle - React, Tailwind, and code Playground

HTML

<div id="tabs" class="ui-layout-center">
    <ul>
        <li><a href="#tab-1">Tab #1</a>
        </li>
        <li><a href="#tab-2">Tab #1</a>
        </li>
    </ul>
    <div id="tab-1" class="customPanel">This content shall: fill up the entire space (left to right) until the bottom of the page. But it shall -NOT- cover the tabs!
        This content shall: fill up the entire space (left to right) until the bottom of the page. But it shall -NOT- cover the tabs!
        This content shall: fill up the entire space (left to right) until the bottom of the page. But it shall -NOT- cover the tabs!
        This content shall: fill up the entire space (left to right) until the bottom of the page. But it shall -NOT- cover the tabs!
        This content shall: fill up the entire space (left to right) until the bottom of the page. But it shall -NOT- cover the tabs!
        This content shall: fill up the entire space (left to right) until the bottom of the page. But it shall -NOT- cover the tabs!
        This content shall: fill up the entire space (left to right) until the bottom of the page. But it shall -NOT- cover the tabs!
        
        This content shall: fill up the entire space (left to right) until the bottom of the page. But it shall -NOT- cover the tabs!
    </div>
    <div id="tab-2" class="customPanel">This content shall: fill up the entire space (left to right) until the bottom of the page. But it shall -NOT- cover the tabs! 
            This content shall: fill up the entire space (left to right) until the bottom of the page. But it shall -NOT- cover the tabs!
        
        This content shall: fill up the entire space (left to right) until the bottom of the page. But it shall -NOT- cover the tabs!
            This content shall: fill up the entire space (left to right) until the bottom of the page. But it shall -NOT- cover the tabs!
        
        This content shall: fill up the entire space (left to right) until the bottom of the page. But it...

CSS

html, body {
    margin: 0;
    padding: 0;
    overflow: hidden;
}
#tabs {
    position: absolute;
    top: 0;
    bottom:0;
    left: 0;
    right: 0;
     overflow:auto;
}

 #tabs .customPanel {
    background: green;
  
}

}

JavaScript

$(function () {
    var tabs = $("#tabs").tabs({});
});