JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
</div>

CSS

.container {
    width: 80%;
    height: 500px;
    margin: 30px auto;
    background: #eee;
    position: relative;
}
.container div {
    float: left;
    width: 25%;
    height: 20%;
    border-right: 2px solid #aaa;
    border-bottom: 2px solid #aaa;
    margin: 0; padding: 0;
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
}
.container div:nth-child(4n) {
    border-right: none;
}
.container div:nth-child(16) ~ div {
    border-bottom: none;
}