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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.

!
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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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.

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HTML 

              
                <section>
  <span>Sticky Header!</span>
</section>
<header>
  <h1>Site Name</h1>
  <nav>
    <a href=#>About</a>
    <a href=#>Services</a>
    <a href=#>Contact</a>
  </nav>
</header>
<article>
  <h1>Headline</h1>
  <p>In elementum lorem eget est euismod ornare. Phasellus sit amet pellentesque mauris. Aliquam quis malesuada ex. Nullam eu aliquam nibh. Mauris molestie, urna accumsan ornare semper, augue nibh posuere lorem, vitae feugiat sem magna eget massa. Vivamus quis tincidunt dolor. Fusce efficitur, orci non vestibulum consequat, lectus turpis bibendum odio, in efficitur leo felis sed justo. Fusce commodo iaculis orci, quis imperdiet urna. Sed mollis facilisis lacus non condimentum. Nunc efficitur massa non neque elementum semper. Vestibulum lorem arcu, tincidunt in quam et, feugiat venenatis augue. Donec sed tincidunt tellus, a facilisis magna. Proin sit amet viverra nibh, bibendum gravida felis. Vivamus ut nunc id mauris posuere pellentesque. Praesent tincidunt id odio id feugiat.</p>
  <p>In ac nisi lacus. Fusce est dolor, tincidunt ut bibendum vitae, fermentum ac quam. Aliquam pretium tristique nibh quis iaculis. In et cursus ex, eu aliquet ex. Proin facilisis lacus sit amet sapien ultrices, ut vehicula arcu lobortis. Vivamus mollis ipsum ut hendrerit molestie. Morbi lacinia, sapien eu dictum dignissim, tellus tortor congue magna, sit amet bibendum libero nisi id massa.</p>
  <p>Donec arcu elit, euismod vel lobortis eu, fringilla sit amet dolor. Cras congue, massa nec sagittis mollis, dui felis ultrices magna, tincidunt finibus lorem quam in sem. Morbi odio turpis, pulvinar sit amet vulputate quis, ultricies eu libero. Donec ac maximus neque, nec maximus nibh. Morbi rhoncus convallis urna, accumsan porta lorem hendrerit in. Cras eget nisl dui. Morbi faucibus nisi eget ipsum semper vulputate. Mauris nec tincidunt lectus. Aenean ac mi consequat velit dignissim consectetur. Fusce placerat ac ipsum ac eleifend. Aenean quis faucibus ex.</p>
  <p>Cras egestas tempor nibh, a fermentum lorem sollicitudin non. Nulla facilisi. In at elit id leo tristique condimentum. Donec at est nulla. Mauris egestas magna ut laoreet pretium. Sed ultrices suscipit vestibulum. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Fusce id sapien eros. Vivamus viverra ultricies gravida. Nam urna nibh, blandit a vulputate at, vehicula non nulla. Aenean ut nulla leo. Praesent in ullamcorper est.</p>
  <p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Phasellus bibendum nec arcu eu lobortis. Nam convallis faucibus ante sed porta. Nullam ut convallis elit, quis venenatis nunc. Curabitur sed sem eget velit condimentum rutrum in et orci. Nunc non suscipit eros. Suspendisse porta sem vel justo commodo dictum. Aliquam erat ligula, fringilla nec suscipit sed, porta vitae turpis. Vestibulum rhoncus placerat nulla vitae suscipit. Curabitur consectetur ex ut odio tristique vehicula. Ut ligula tortor, tincidunt quis sodales vitae, ornare a turpis. Proin sit amet finibus enim. Fusce tempus a neque vitae tempor. Aenean rutrum, libero iaculis interdum vulputate, dui eros vehicula nisi, at interdum enim lacus eu diam.</p>
</article>
!

CSS 

              
                * {
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  font-kerning: auto;
}
html {
  font-size: 10pt;
  line-height: 1.4;
  font-weight: 400;
  font-family: 'Source Sans Pro', 'Open Sans', Roboto, 'HelveticaNeue-Light', 'Helvetica Neue Light', 'Helvetica Neue', 'Myriad Pro', 'Segoe UI', Myriad, Helvetica, 'Lucida Grande', 'DejaVu Sans Condensed', 'Liberation Sans', 'Nimbus Sans L', Tahoma, Geneva, Arial, sans-serif;
  -webkit-text-size-adjust: 100%;
}
body {
  margin: 0;
  background: #eee;
}
section {
  height: 100vh;
  background: coral;
}
section span {
  margin: 0;
  font-size: 400%;
  text-align: center;
  line-height: 1;
  padding-top: calc(50vh - 20pt);
  display: block;
  font-weight: 700;
}
header {
  width: 100%;
  padding: 1em;
  font-size: 140%;
  position: absolute;
  top: 100vh;
  left: 0;
  transition: opacity .2s ease-in-out;
  text-align: center;
}
header h1 {
  font-weight: 600;
  display: inline;
  margin: 0;
  padding: 0;
  font-size: inherit;
}
nav a {
  display: inline-block;
  outline: none;
  text-decoration: none;
  opacity: .7;
  padding: 0 .5em;
  color: black;
  transition: opacity .2s ease-in-out;
}
nav a:hover,
nav a:focus {
  opacity: 1;
}
article {
  margin: 5em auto 0;
  padding: 1em;
  font-size: 140%;
  max-width: 800px;
  background: white;
  box-shadow: rgba(0,0,0,.05) 0 3px 15px;
}
article p {
  margin: 0;
  color: #333;
}
article p + p {
  margin-top: .7em;
}
@media (min-width: 500px) {
  header {
    text-align: left;
  }
  nav {
    float: right;
  }
  article {
    margin: 3.5em auto 0;
    padding: 2em;
  }
}
@media (min-width: 800px) {
  article {
    margin: 3.5em auto;
  }
}

/* And here's the magic! EQCSS.js required */
@element html, body and (min-scroll-y: 100vh) {
  header {
    position: fixed;
    top: 0;
    background: white;
    box-shadow: rgba(0,0,0,.05) 0 3px 15px;
  }
}
!

JS
!
999px

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