JSFiddle - React, Tailwind, and code Playground

by Gagan Gami

HTML

<input type="button" id="fontPlusBtn" value="Increase"/>
<div id="textDiv">
    <span class="first">text1</span>
    <span class="second">text2</span>
</div>

CSS

#textDiv {
    font-size: 12px;
}

.first {
    font-size: 12px;
}

.second {
    font-size: 30px;
}

JavaScript

$("#fontPlusBtn").click(function (){
    $("#textDiv > *").css("font-size", function(i, value) {
        return parseInt(value) * 1.1;
    });
});