是否可以使用 CSS 隐藏
除 intro-class 及其子元素之外的所有 body 内部元素？
body *:not(.intro > *) {
opacity: 0;
}<body>
<h1>Welcome to My Homepage</h1>
<div class="intro">
<p id="firstname">My name is Donald.</p>
<p id="hometown">I live in Duckburg.</p>
</div>
<p>My best friend is Mickey.</p>
</body>