JSFiddle - React, Tailwind, and code Playground
HTML
<input id="rad1" type="radio" name="rad"><label for="rad1">Radio 1</label>
<input id="rad2" type="radio" name="rad"><label for="rad2">Radio 2</label>
CSS
input[type="radio"]:checked+label{ font-weight: bold; }
//a label that immediately follows an input of type radio that is checked