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HTML

About HTML Preprocessors

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

In CodePen, whatever you write in the HTML editor is what goes within the <body> tags in a basic HTML5 template. So you don't have access to higher-up elements like the <html> tag. If you want to add classes there that can affect the whole document, this is the place to do it.

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

The resource you are linking to is using the 'http' protocol, which may not work when the browser is using https.

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-.

We offer two popular choices: Autoprefixer (which processes your CSS server-side) and -prefix-free (which applies prefixes via a script, client-side).

Add External Stylesheets/Pens

Any URLs added here will be added as <link>s in order, and before the CSS in the editor. You can use the CSS from another Pen by using its URL and the proper URL extension.

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About External Resources

You can apply CSS to your Pen from any stylesheet on the web. Just put a URL to it here and we'll apply it, in the order you have them, before the CSS in the Pen itself.

You can also link to another Pen here (use the .css URL Extension) and we'll pull the CSS from that Pen and include it. If it's using a matching preprocessor, use the appropriate URL Extension and we'll combine the code before preprocessing, so you can use the linked Pen as a true dependency.

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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.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

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About External Resources

You can apply a script from anywhere on the web to your Pen. Just put a URL to it here and we'll add it, in the order you have them, before the JavaScript in the Pen itself.

If the script you link to has the file extension of a preprocessor, we'll attempt to process it before applying.

You can also link to another Pen here, and we'll pull the JavaScript from that Pen and include it. If it's using a matching preprocessor, we'll combine the code before preprocessing, so you can use the linked Pen as a true dependency.

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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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About Packages

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.

If you're using React / ReactDOM, make sure to turn on Babel for the JSX processing.

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HTML 

              
                <section class="content">
  <a href="#" id="trigger">Menu</a>
  <ul id="menu">
    <li class="menu-item"><a href="#anchor">Anchor link</a></li>
    <li class="menu-item"><a href="/example">Non-anchor link</a></li>
  </ul>
  <div>
    <p>Filler content.</p>
    <p>Fusce vel pulvinar libero, vitae dignissim quam. Nunc ut fermentum libero. Aenean odio sem, fringilla eu eros at, eleifend egestas libero. Curabitur nec cursus lorem. Integer scelerisque sed orci sit amet consectetur.</p>
  </div>
  <div id="anchor">
    <p>Anchor content.</p>
    <p>Filler content. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Pellentesque nisi lacus, rhoncus vitae leo eu, maximus varius urna. Pellentesque tempor felis ac egestas dapibus. Quisque ullamcorper sem porttitor ornare porttitor. Suspendisse vitae blandit justo, a sollicitudin tortor. Sed leo lorem, cursus id sapien quis, tincidunt fringilla leo. Suspendisse fermentum massa vel ultrices rutrum. Nunc tincidunt, quam ut sagittis molestie, ipsum arcu consectetur nunc, et venenatis elit purus eget neque. Maecenas lobortis hendrerit auctor. Fusce vel pulvinar libero, vitae dignissim quam. Nunc ut fermentum libero. Aenean odio sem, fringilla eu eros at, eleifend egestas libero. Curabitur nec cursus lorem. Integer scelerisque sed orci sit amet consectetur.</p>
    <p>Cras non efficitur lorem. Sed eu nisi ex. Fusce id mi vitae justo dapibus iaculis in eu nibh. Vivamus eget eros quis tortor tristique mattis non et mauris. Donec scelerisque quis justo sit amet porttitor. Phasellus scelerisque dolor sit amet bibendum vulputate. Etiam nec ligula neque. Aenean et enim nisl. Sed aliquam quam non turpis suscipit, ac convallis lacus commodo. Aenean vestibulum nisi eget lobortis auctor. Proin quis dui quam. Donec ut tortor mollis, maximus nunc vitae, commodo elit. Donec scelerisque massa faucibus risus iaculis pretium. Morbi hendrerit lorem nec dolor interdum venenatis a vel mauris. Vivamus dictum volutpat ex id semper. Mauris rhoncus lorem at turpis efficitur, non ultricies sem porttitor.</p>
    <p> Maecenas id semper neque. Sed blandit nisi vitae pharetra tincidunt. Maecenas sapien augue, pretium non felis vitae, pellentesque aliquam velit. Sed vel lectus nisi. Pellentesque eleifend posuere nisl. Praesent ornare nunc eu sapien vulputate dapibus. Sed aliquam efficitur viverra. Ut auctor massa hendrerit sapien molestie laoreet. Aliquam facilisis felis vel molestie tincidunt. Donec vel elit mauris. Proin imperdiet magna eget sapien lobortis, sit amet venenatis ex feugiat.</p>
    <p>Fusce fermentum convallis dapibus. Aliquam maximus tincidunt sollicitudin. Suspendisse fringilla pulvinar ornare. Aliquam nulla turpis, laoreet vitae lobortis eget, imperdiet in nunc. Duis eu tempus libero. Morbi consectetur convallis vestibulum. Nulla fringilla orci nec magna euismod scelerisque. Morbi id iaculis sem. Duis varius ultricies malesuada. Nunc id ornare ante, sed varius turpis. Fusce vitae tristique dui. Praesent nec nunc semper, pretium velit et, sodales nisl. Nullam vulputate ex eget volutpat lacinia. Donec vitae ornare mi. Quisque sed nisi vitae eros luctus pulvinar.</p>
  </div>
</section>
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CSS 

              
                .content {
  position: relative;
}
#trigger:after {
  content: '+';
}
#trigger.open:after {
  content: '-';
}
#menu { 
  display: none; 
}
#menu.open { 
  display: block; 
  position: absolute; top: 2.4em; left: 0;
  height: 100%;
  width: 70%;
}

/* Other styles */
html { 
  background: #00ced1;
}
body {
  font-family: 'Open Sans', Helvetica, Arial, sans-serif;
  margin: 0;
}
.content { 
  background: white;
  margin: 0 auto; 
  min-width: 500px;
  width: 50%; 
}
#trigger, #menu {
  background: #000;
  color: #fff;
  font-weight: bold;
}
#trigger {
  display: block;
  padding: 1em;
  text-decoration: none;
  text-transform: uppercase;
}
#trigger:after {
  float: right;
}
#menu { 
  list-style: none; 
  padding: 0; 
}
#menu li { 
  padding: .5em 1em; 
}
#menu a {
  color: #fff;
}
div {
  padding: 0 1em;
}
div#anchor {
  padding-bottom: 1em;
}
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JS 

              
                // Set up variables
var menuTrigger = document.getElementById('trigger');
var menuContent = document.getElementById('menu');
var menuItems = document.getElementsByClassName('menu-item');

// Basic menu toggle
function menuToggle() {
  menuTrigger.classList.toggle('open');
  menuContent.classList.toggle('open');
}

// Toggle menu on trigger click
menuTrigger.onclick = function(){
  menuToggle();
}

// Toggle menu on same-page anchor click
var windowHref = window.location.protocol + '//' + window.location.host + window.location.pathname; // Don't include any existing anchors in URL

for (var i = 0; i < menuItems.length; i++) {
  menuItems[i].onclick = function(e){
    var linkHref = this.getElementsByTagName('a')[0].href;
    if (linkHref.indexOf(windowHref) > -1) { // If the window's URL is found within the menu item's URL, toggle the menu
      menuToggle();
    }
  }
}
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999px

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