JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <div style="width: 800px; height:800px; border: solid 1px #000; position:relative;">
        <div style="width:300px; height:700px; bottom:0; border: solid 1px #000; overflow:scroll; position:absolute;" id="swindow">
            <div>
               <p> Human habitation of the Australian continent is estimated to have begun between 42,000 and 48,000 years ago,[32][33] possibly with the migration of people by land bridges and short sea-crossings from what is now Southeast Asia. These first inhabitants may have been ancestors of modern Indigenous Australians.[34] At the time of European settlement in the late 18th century, most Indigenous Australians were hunter-gatherers, with a complex oral culture and spiritual values based on reverence for the land and a belief in the Dreamtime. The Torres Strait Islanders, ethnically Melanesian, were originally horticulturalists and hunter-gatherers.[35] The northern coasts and waters of Australia were visited sporadically by fishermen from Maritime Southeast Asia.[36]
The first recorded European sighting of the Australian mainland, and the first recorded European landfall on the Australian continent, are attributed to the Dutch navigator Willem Janszoon. He sighted the coast of Cape York Peninsula in early 1606, and made landfall on 26 February at the Pennefather River near the modern town of Weipa on Cape York.[37] The Dutch charted the whole of the western and northern coastlines and named the island continent "New Holland" during the 17th century, but made no attempt at settlement.[37] William Dampier, an English explorer and privateer, landed on the north-west coast of New Holland in 1688 and again in 1699 on a return trip.[38] In 1770, James Cook sailed along and mapped the east coast, which he named New South Wales and claimed for Great Britain.[39] With the loss of its American colonies in 1783, the British Government sent a fleet of ships, the "First Fleet", under the command of Captain Arthur Phillip, to...

JavaScript

function init(){
     $("#btn").click(function(){
         var newH = 300;
         $("#swindow").css("height",newH+"px");
         //$("#swindow div").css("top","-300px");
         var x = $("#swindow").scrollTop()+newH+100 ;
         $("#swindow").scrollTop(x);
         //alert($("#swindow").scrollTop());
         //alert("Done");
     }); 
}

init();