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.

              body {
  font-family: sans-serif;
  font-size: 20px; /* the new 16px */

.tooltip-trigger-text {
  border-bottom: 1px dashed grey;

.tooltip-body {
  position: fixed;
  padding: 8px;
  background: #333;
  color: white;
  box-shadow: 2px 2px 3px rgba(0 ,0, 0, 0.3);
  text-align: center;
  font-size: 16px;
              class MyPortal extends React.PureComponent {
  constructor(props) {
    this.el = document.createElement('div');

  componentDidMount() {

  componentWillUnmount() {
  render() {
    return ReactDOM.createPortal(this.props.children, this.el);

class Tooltip extends React.PureComponent {
  constructor(props) {
    this.state = {
      visible: false,
    this.width = props.width || 256;
    this.space = props.space || 16;
    this.showTooltip = this.showTooltip.bind(this);
    this.hideTooltip = this.hideTooltip.bind(this);
  showTooltip() {
    // some maths to align the tooltip with whatever you just hovered over (the 'target')
    // or maybe it's 'math' in your weird country
    const style = { width: this.width }; // this style object will be passed as the tooltip's 'style' prop
    const dimensions = this.el.getBoundingClientRect(); // where on the screen is the target
    // center align the tooltip by taking both the target and tooltip widths into account
    style.left = (dimensions.left + (dimensions.width / 2)) - (this.width / 2);
    style.left = Math.max(this.space, style.left); // make sure it doesn't poke off the left side of the page
    style.left = Math.min(style.left, document.body.clientWidth - this.width - this.space); // or off the right
    if (dimensions.top < window.innerHeight / 2) { // the top half of the page
      // when on the top half of the page, position the top of the tooltip just below the target (it will stretch downwards)
      style.top = dimensions.top + dimensions.height + this.space;
    } else {
      // when on the bottom half, set the bottom of the tooltip just above the top of the target (it will stretch upwards)
      style.bottom = (window.innerHeight - dimensions.top) + this.space;
      visible: true,
  hideTooltip() {
    this.setState({visible: false});
  render() {
    return (
      <span // a span so it's valid HTML no matter where it's used
        ref={el => this.el = el}
        {this.state.visible && (
            <div // this <div> isn't actually a child of the <span> above. Magic portal.

const App = () => (
      Some text, some of which <Tooltip text="This is some more info about that first thing that you should find every interesting.">requires explanation.</Tooltip> (Scroll down for more.)
    <div style={{ lineHeight: 80 }}>Scroll down</div>
      <Tooltip text="You hovered over the second one!">Something else to hover over</Tooltip> is what this is.
    <div style={{ lineHeight: 80 }}>Just more paddin'</div>

ReactDOM.render(<App/>, document.getElementById('root'));

🕑 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.