JSFiddle - React, Tailwind, and code Playground
HTML
<script>
function boldText(checkBox,target){ if(checkBox.checked){
document.getElementById(target).style.fontWeight = "bold"; }
else
{ document.getElementById(target).style.fontWeight = "normal"; } }
</script>
<input type="checkbox" onclick="boldText(this,'lineOne')">
<div id="lineOne">Change text to bold</div>
<input type="checkbox" onclick="boldText(this,'linetwo')">
<div id="linetwo">Change text to bold</div>