.p-anima-4 {
  display: flex;
  justify-content: center;
}
.p-anima-4 span {
  display: block;
  color: #fff;
  background-color: #333;
  font-size: 20px;
  font-weight: bold;
  padding: 2px 8px;
  position: relative;
  clip-path: inset(0 100% 0 0);
}
.p-anima-4.__anima span {
  animation: anima_4 0.4s linear forwards;
}

@keyframes anima_4 {
  0% {
    clip-path: inset(0 100% 0 0);
  }
  100% {
    clip-path: inset(0);
  }
}

/* アニメーションとは関係のないスタイル（ボタンの見た目など） */
body {
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  height: 100vh;
}
button {
  margin-top: 40px;
}

document.querySelector('#js-reload').addEventListener('click', (_ev) => {
  const target = _ev.target.getAttribute('data-reload');
  document.querySelector(`#${target}`).classList.remove('__anima');
  setTimeout(() => {
    document.querySelector(`#${target}`).classList.add('__anima');
  }, 500);
});