<div>
<p id="sample-text">HELLO WORLD</p>
<button id="sample-btn">小文字に変換</button>
</div>*{
text-align:center;
}const text = document.getElementById('sample-text');
const btn = document.getElementById('sample-btn');
btn.addEventListener('click',function(){
text.innerHTML = text.innerHTML.toLowerCase();
})
External CSS
This Pen doesn't use any external CSS resources.