JSFiddle - React, Tailwind, and code Playground

HTML

<body>
    <content>
        <div id="box1" class="box">A: <span class="num">0</span></div>
        <div id="box2" class="box">B: <span class="num">0</span></div>
        <div id="box3" class="box">C: <span class="num">0</span></div>
    </content>
</body>

CSS

content {
    display: -moz-box;
    display: -webkit-box;
    display: box;
    box-orient: horizontal;
    width: 100%;
    height : 100%;
}

div {
    -moz-box-flex: 1;
    -webkit-box-flex: 1;
    box-flex: 1;
    height: 100px;
}

#box1 {
    background : #FCC;
}

#box2{
    background : #CFC;
}

#box3{
    background : #CCF;
}

JavaScript

$( function() {
   
    $('.box').click( function() {
        var num = $(this).find('.num');
        num.text( parseInt(num.text()) + 1 );
    });
    
});