<!-- Hello world! This is my answer for "Animate <details> tag".
It's a pretty good option to do this.
Sorry the CSS is minified... To get the formatted css version, google
"greeper 27520274".
-->
<article>
<h1>How to create a pop-up without JavaScript</h1>
<p>Ever wanted a pop-up mechanism on your website, but you don't want to use JavaScript? Here's how:</p>
<ol>
<li>Add a <code><details></code> and <code><summary></code> to your document</li>
<li>Insert a <code><div></code> to your <code><details></code> element</li>
<li>Add a scaling animation to this <code><div></code></li>
<li>Add this animation to the <code><div></code> when the <code>[open]</code> attribute is toggled on the <code><details></code> element</li>
</ol>
<p>Toggle the <strong>How it works</strong> button for more info.</p>
</article>
<details>
<summary>How it works<svg xmlns="http://www.w3.org/2000/svg" width="192" height="192" fill="currentColor" viewBox="0 0 256 256"><rect width="256" height="256" fill="none"></rect><circle cx="128" cy="128" r="96" fill="none" stroke="currentColor" stroke-linecap="round" stroke-linejoin="round" stroke-width="16"></circle><circle cx="128" cy="180" r="12"></circle><path d="M127.9995,144.0045v-8a28,28,0,1,0-28-28" fill="none" stroke="currentColor" stroke-linecap="round" stroke-linejoin="round" stroke-width="16"></path></svg></summary>
<div>
<p>Hello world!</p>
</div>
</details>
<style>
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</style>