JSFiddle - React, Tailwind, and code Playground

HTML

<div>
  <p>Привет, стиль..</p>
</div>

<button id="test">test</button>

CSS

div {
  transition: opacity 1s ease;
}

JavaScript

test.onclick = () => {
  document.getElementsByTagName("div")[0].style.opacity = "0";
  setTimeout(() => {
    document.getElementsByTagName("div")[0].style.opacity = "1";
  }, 1000);
};