JSFiddle - React, Tailwind, and code Playground

HTML

<div>
Hi - testing testing
</div>
<button id='inc'>Increase Text Size</button>
<button id='dec'>Decrease Text Size</button>

JavaScript

var size = 10;

function setFontSize(s) {
    size = s;
    $('body').css('font-size', '' + size + 'px');
}

               
function increaseFontSize() {
    setFontSize(size + 5);
}
    
function decreaseFontSize() {
    if(size > 5)
        setFontSize(size - 5);
}
    
$('#inc').click(increaseFontSize);
$('#dec').click(decreaseFontSize);
setFontSize(size);