JSFiddle - React, Tailwind, and code Playground

HTML

<div id="A1-result" class="test">
        <div class="online">0</div>
        <div class="online">1</div>
        <div class="online">2</div>
        <div class="online">3</div>     
    </div>
    <div id="A2-result" class="test">
        <div class="online">4</div>
        <div class="online">5</div>
        <div class="online">6</div>
        <div class="online">7</div>
    </div>
    <div id="A3-result" class="test">
        <div class="online">8</div>
        <div class="online">9</div>
        <div class="online">10</div>
        <div class="online">11</div>        
    </div>
    <div id="A4-result" class="test">
        <div class="online">12</div>
        <div class="online">13</div>
        <div class="online">14</div>
        <div class="online">15</div>
    </div>

CSS

.wrap {
    white-space: normal !important;
    }
.online {
    border-radius: 5px; 
    -moz-border-radius: 5px; 
    -webkit-border-radius: 5px; 
    border: 2px solid #00CC00;
    width: 20px;
    text-align: center;
    padding: 2px;
    display: inline-block;
}
.test {
    display: inline-block;
}