JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li>1. Some text</li>
    <li>2. Some text</li>
    <li>3. Some text</li>
    <li>4. Some text</li>
</ul>

CSS

li:first-letter {
    color:blue;
}
.selected {
    background-color:#eee;
}
.selected:first-letter {
    color:inherit;
}

JavaScript

$('li').click(function () {
    $('li.selected').removeClass('selected');
    $(this).toggleClass('selected');
});