JSFiddle - React, Tailwind, and code Playground

HTML

<section class="products">
    <article class="product-single  cf">1</article><article class="product-single  cf">2</article><article class="product-single  cf">3</article><article class="product-single  cf">4</article><article class="product-single  cf">5</article><article class="product-single  cf">6</article><article class="product-single  cf">7</article><article class="product-single  cf last3 ">8</article><article class="product-single cf">9</article></section>

CSS

* {
 -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    -o-box-sizing: border-box;
    -ms-box-sizing: border-box;
    box-sizing: border-box;
}
section.products {
width: 100%;        
}
section.products article.product-single  {
    width: 33.3333%;
    padding: 2%;
    display: inline-block;
    vertical-align: top;
    position: relative;
    min-height: 260px;
    border-bottom: 1px solid red;
    border-right: 1px solid red;
    position: relative;
}

section.products article.product-single:nth-child(3n) {
    border-right: none;
}

section.products article.lastrow{
    border-bottom: none;
}