Pen Settings

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URL's added here will be added as <link>s in order, and before the CSS in the editor. If you link to another Pen, it will include the CSS from that Pen. If the preprocessor matches, it will attempt to combine them before processing.

+ add another resource

You're using npm packages, so we've auto-selected Babel for you here, which we require to process imports and make it all work. If you need to use a different JavaScript preprocessor, remove the packages in the npm tab.

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.

+ add another resource

Use npm Packages

We can make npm packages available for you to use in your JavaScript. We use webpack to prepare them and make them available to import. We'll also process your JavaScript with Babel.

⚠️ This feature can only be used by logged in users.

Code Indentation


Save Automatically?

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

HTML Settings

Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

              <p>The [note] sign is historically equal to the asterisks used by Aristarchus of Samothrace at the Mouseion at Alexandria. It was used for the critical editions of Homer's writings where it "marked a verse incorrectly repeated in another passage" and was used together with other signs such as the obelus.<a class="annotation-link" href="#"><sup>1</sup></a>

  <span class="annotation">
   <a href="#">L.D. Reynolds and N.G. Wilson</a>. <i>Scribes and Scholars: A guide to the Transmission of Greek and Latin Literature</i>. Oxford University Press, 1991, 3rd edition, ISBN 0-19-872146-3, p. 10-11

The London printer Richard Jugge is generally credited as the inventor of the footnote, first used in the Bishops' Bible of 1568.<a class="annotation-link" href="#"><sup>2</sup></a>

  <span class="annotation">
    Chuck Zerby, <i><a href="#">The Devil's Details: A History of Footnotes</a></i>, 2007, ISBN 1931229058, p. 28 and <i>passim</i>

<p>Early printings of the Douay Bible used two closely spaced colons (actually squared four dot punctuation mark U+2E2C) to indicate a marginal note. (Source: <a href="https://en.wikipedia.org/wiki/Note_(typography)">Wikipedia</a>)</p>
              // Styling only
body { 
  font: 1.1rem/130% sans-serif;
  line-height: 160%;
  padding: 3rem;

sup { 
  line-height: 1; 
  margin: 0 2px;

.annotation {
  color: grey;
  cursor: default;
  display: block;
  font-family: sans-serif;
  font-size: 0.9rem;
  padding: 0.5rem 0;

// Functional classes
.annotation-link-selected { 
  sup { 
    opacity: 0; 
  &:after {
    content: "x";
    display: inline-block;
    margin: -7px 0 0 -9px;
    opacity: 1;
    vertical-align: top;

// Uses the max-height hack: http://bit.ly/2mpGSwW
.annotation { 
  display: none;
  max-height: 0;
  opacity: 0;
  overflow: hidden;
    max-height .3s ease-out 0s,
    width .01s ease-out .3s,
    opacity .2s ease-out 0s;
  width: 0;

.annotation-expanded {
  max-height: 5000px;
  width: 100%;
  opacity: 1;
    max-height .5s ease-in .01s,
    width .01s ease-in 0s,
    opacity .2s ease-in-out .21s;

.annotation-displayed { display: block; }
              // helper
const selectAll = (selector, root = document) => {
  return Array.prototype.slice.call(root.querySelectorAll(selector), 0)

// select annotations and annotation links
const annotationLinks = selectAll('.annotation-link')
const annotations = selectAll('.annotation')

const toggleAnnotation = ({ currentTarget: el }) => {
  const annotationLinkId = el.dataset.id
  const isSelected = el.classList.contains('annotation-link-selected')
  const annotationContainer = document.querySelector(`.annotation[data-id="${annotationLinkId}"]`)

  if (isSelected) {
    setTimeout(() => { annotationContainer.classList.toggle('annotation-displayed') }, 300)
  } else {
    setTimeout(() => { annotationContainer.classList.toggle('annotation-expanded') }, 300)

const closeAnnotation = ({ currentTarget: el }) => {

  // https://developer.mozilla.org/en-US/docs/Web/API/Window/getSelection  
  if (window.getSelection().type === "Range") { return }
  const annotationContainerId = el.dataset.id
  const annotationLink = document.querySelector(`.annotation-link[data-id="${annotationContainerId}"]`)
  setTimeout(() => { el.classList.toggle('annotation-displayed') }, 300)

// Loop through all annotation links
annotationLinks.forEach((el, index) => {
  // Adds matching data ids to annotations and containers
  el.setAttribute('data-id', index + 1)

  // Clicking an annotation link expands/collapses the annotation
  el.addEventListener('click', toggleAnnotation)

// Loop through all annotations
annotations.forEach((el, index) => {
  // Adds matching data ids to annotations and containers
  el.setAttribute('data-id', index + 1)

  // Clicking the content of an annotation collapses it, too
  el.addEventListener('click', closeAnnotation)

  // Prevent annotation from hiding if link in annotation is clicked
  el.querySelector('a').addEventListener('click', e => e.stopPropagation())  

🕑 One or more of the npm packages you are using needs to be built. You're the first person to ever need it! We're building it right now and your preview will start updating again when it's ready.