JSFiddle - React, Tailwind, and code Playground

HTML

<button id="a">click me</button>
<button id="b">click me</button>

CSS

.focus {
    border: 5px solid red !important;
}
:focus {
    background: hotpink !important;
}

JavaScript

var b = document.getElementById( "b" );
b.addEventListener( "click", function() {
    b.disabled = true;
    b.classList.add( "focus" );
});
b.addEventListener( "blur", function() {
    b.classList.remove( "focus" ); 
});