JSFiddle - React, Tailwind, and code Playground
by Lucas Krause
HTML
<span>1</span><div></div>
<span>2</span><div></div>
<b>3</b><div></div>
<span>4</span><div></div>
<i>5</i><div></div>
<em>6</em><div></div>
<strong>7</strong><div></div>
<span>8</span><div></div>
<code>9</code><div></div>
<span>10</span><div></div>
<span>11</span><div></div>
<span>12</span><div></div>
<span>13</span><div></div>
<span>14</span><div></div>
CSS
:nth-child(3n+3) {
color:red;
}
div:nth-of-type(3n){
height:1px;
background-color:red;
}