style에 적합한 도구는 CSSanimation에 적합한 도구는 JS step 1. Find the element.step 2. Listen for an event.step 3. React to that event. (show, hide, change color of sth, ...) const h1 = document.querySelector("div.hello:first-child h1")function handleTitleClick() { // change color const currentColor = h1.style.color // getter let newColor if (currentColor === 'blue') { newColor = 'tomato' ..