JSFiddle - React, Tailwind, and code Playground

HTML

<div id="root" tabindex="1">
    <div>DIV A</div> <a class="hidden" href="http://www.google.com">LINK</a>

    <div class="hidden">DIV B</div>
    <input class="hidden" type="submit" value="input" />
</div>

CSS

.hidden {
    color: red;
    display: none;
}
#root:FOCUS .hidden {
    display: block;
}

JavaScript

function focusRoot(e) {
        e.currentTarget.parentElement.focus();
        return;
    }
    var root = document.getElementById('root');
    var cs = root.children;
    for (var i = 0; i < cs.length; i++) {
        var c = cs[i];
        c.onfocus = focusRoot;
    }