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HTML

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HTML preprocessors can make writing HTML more powerful or convenient. For instance, Markdown is designed to be easier to write and read for text documents and you could write a loop in Pug.

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Adding Classes

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About the <head>

In CodePen, whatever you write in the HTML editor is what goes within the <body> tags in a basic HTML5 template. If you need things in the <head> of the document, put that code here.

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Insecure Resource

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CSS

About CSS Preprocessors

CSS preprocessors help make authoring CSS easier. All of them offer things like variables and mixins to provide convenient abstractions.

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CSS Base

About CSS Base

It's a common practice to apply CSS to a page that styles elements such that they are consistent across all browsers. We offer two of the most popular choices: normalize.css and a reset. Or, choose Neither and nothing will be applied.

Vendor Prefixing

About Vendor Prefixing

To get the best cross-browser support, it is a common practice to apply vendor prefixes to CSS properties and values that require them to work. For instance -webkit- or -moz-.

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JavaScript

About JavaScript Preprocessors

JavaScript preprocessors can help make authoring JavaScript easier and more convenient.

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Babel includes JSX processing.

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Packages

Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.

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Using packages here is powered by esm.sh, which makes packages from npm not only available on a CDN, but prepares them for native JavaScript ESM usage.

All packages are different, so refer to their docs for how they work.

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HTML 

              
                <div class="accordion-container">
  <div class="accordion-header">
    <i class="fa fa-angle-right"></i> Comment préparer un bon régime alimentaire ?
  </div>
  <div class="accordion-content">Lorem ipsum dolor sit amet, consectetur adipiscing elit. Quisque eget tellus eget ex gravida fringilla. Pellentesque semper augue ac nunc viverra, sit amet aliquam odio hendrerit. Mauris tempus at risus.</div>
  <div class="accordion-header">
    <i class="fa fa-angle-right"></i> Pourquoi suivre un régime alimentaire ?
  </div>
  <div class="accordion-content">Duis scelerisque lectus ipsum, in laoreet diam feugiat id. Integer dapibus mauris justo, vel feugiat elit facilisis non. Maecenas ac eros eu arcu volutpat congue vel ut massa. Pellentesque habitant.</div>
  <div class="accordion-header">
    <i class="fa fa-angle-right"></i> Avec quoi préparer un bon régime alimentaire ?
  </div>
  <div class="accordion-content">Nulla a massa massa. Sed ultrices porta nisi, vel eleifend metus volutpat sed. Integer eget urna lorem. Etiam bibendum ante at neque dignissim efficitur. Phasellus iaculis, massa eu porta tincidunt.</div>
  <div class="accordion-header">
    <i class="fa fa-angle-right"></i> Où trouver des recettes pour un bon régime alimentaire ?
  </div>
  <div class="accordion-content">Phasellus faucibus suscipit est id lacinia. Suspendisse ultricies fermentum turpis, non lobortis sapien ultricies a. Integer sodales at sapien ut gravida. Sed pellentesque rhoncus arcu. Vestibulum maximus, felis dictum cursus.</div>
</div>

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.15.1/css/all.min.css" integrity="sha512-+4zCK9k+qNFUR5X+cKL9EIR+ZOhtIloNl9GIKS57V1MyNsYpYcUrUeQc9vNfzsWfV28IaLL3i96P9sdNyeRssA==" crossorigin="anonymous" />
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CSS 

              
                .accordion-header {
  background-color: #f2f2f2;
  color: #444;
  cursor: pointer;
  padding: 18px;
  width: 100%;
  border: none;
  text-align: left;
  outline: none;
  font-size: 15px;
  transition: 0.4s;
}

.accordion-header:hover {
  background-color: #ddd;
}

.accordion-header i {
  margin-right: 10px;
}

.accordion-content {
  padding: 0 18px;
  background-color: white;
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.2s ease-out;
}

@media (max-width: 767px) {
  .accordion-header {
    font-size: 18px;
  }
}

@media (min-width: 768px) {
  .accordion-header {
    font-size: 22px;
  }
}
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JS 

              
                 const headers = document.querySelectorAll(".accordion-header");
  headers.forEach(header => {
    header.addEventListener("click", function() {
      this.classList.toggle("active");
      const content = this.nextElementSibling;
		if (content.style.maxHeight) {
			content.style.maxHeight = null;
			this.querySelector("i").classList.remove("fa-angle-down");
			this.querySelector("i").classList.add("fa-angle-right");
		} else {
			content.style.maxHeight = content.scrollHeight + "px";
			this.querySelector("i").classList.remove("fa-angle-right");
			this.querySelector("i").classList.add("fa-angle-down");
		}
	});
});
!
999px

Console