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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.

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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.

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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.

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Code Indentation


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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.

              (function() {
  'use strict';

  // throttled value before window event starts
  var throttled; 
  // Delay function calls to 66ms (frame rate: 15fps)
  var delay = 66; 
  // Declare empty variable for later use
  var resizeTimeout;

  // Grab body element
  var body = document.querySelector('body');
  // Create element
  var viewportDimensions = document.createElement('div');

  // Style element
  viewportDimensions.style.position = 'fixed';
  viewportDimensions.style.right = 0;
  viewportDimensions.style.top = 0;
  viewportDimensions.style.padding = '16px';
  viewportDimensions.style.zIndex = 3;
  viewportDimensions.style.fontSize = '22px';

  // Add div element inside body element

  // window.resize callback function
  function getViewportDimensions() {
    var width = window.innerWidth;
    var height = window.innerHeight;

    viewportDimensions.textContent = width + 'px' + ' x ' + height + 'px';
    viewportDimensions.style.display = 'block';

    resizeTimeout = setTimeout(removeViewportDimensions, 3000);

  // Called from getViewportDimensions()
  function removeViewportDimensions() {
    viewportDimensions.style.display = 'none';

  function throttler() {
    // Only run code if’s block if we’re not throttled
    if (!throttled) {
      // Callback: the function we want to throttle
      // We're currently throttled!
      throttled = true;
      // Reset throttled variable back to false after delay
      setTimeout(function() {
        throttled = false;
      }, delay);

  // Listen to resize event, and run throttler()
  window.addEventListener('resize', throttler);

  // End of IFFE wrapper

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