Pen Settings



CSS Base

Vendor Prefixing

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.

+ add another resource


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.

+ add another resource


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.


Auto Save

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.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.


                <p>Default input examples with the chained :not selector. Only the inputs we expect have a red border and not the ones we specifically excluded with our :not selector</p>
<input />
<input type="email" />
<input type="file" />
<input type="submit" />
<p>With the .override class, you might think that every input below would now have a blue border, but due to the increased specificity of the chained :not selector, that is not the case.</p>
<p>The first two inputs still have the red border from the chained :not selector even though they also have the .override class applied to them.<p>
<input class="override" />
<input class="override" type="email" />
<input class="override" type="file" />
<input class="override" type="submit" />
<p>Check out <a href=""></a> to see how this can be fixed using the :where selector</p>


                /* Chained :not selectors applying a red border to all inputs except the ones listed in the :not selectors below */
input:not([type="hidden"]):not([type="checkbox"]):not([type="radio"]):not([type="file"]):not([type="range"]):not([type="submit"]):not([type="reset"]):not([type="image"]) {
  border: 1px solid #f00;

/* Override class will not override styles above due to specificity of chained :not selectors */
.override {
  border: 1px solid #00F;

/* Check out to see how this can be fixed using the :where selector */