JSFiddle - React, Tailwind, and code Playground

HTML

<div id="portfolio">
			<div>cell 1</div>
			<div>cell 2</div>
			<div>cell 3</div>
			<div>cell 4</div>
			<div>cell 5</div>
			<div>cell 6</div>
			<div>cell 7</div>
		</div>

CSS

#portfolio {
    display: flex;
    flex-flow: row wrap;
  text-align: center;
}
#portfolio > div {
  flex: 1 1 33%;
  background-color: #fff;
  border: 1px solid #000;
}