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CSS Base

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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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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.

            
              <main>
  <toggle-section open="false">
    <h2 id="section-1">Section 1</h2>
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nam non lectus sit amet nunc facilisis molestie. Praesent quis libero et mauris facilisis dignissim at sed nisi.</p> 
    <p>Nullam efficitur porttitor lectus, ac finibus nibh fermentum ac. Phasellus aliquam, nibh non efficitur pharetra, tellus diam posuere lectus, a consequat elit ex nec ligula.</p>
  </toggle-section>
  <toggle-section open="true">
    <h2 id="section-2">Section 2</h2>
    <p>Aliquam erat volutpat. Nulla facilisi. Nunc porttitor, elit non eleifend aliquam, est leo scelerisque nibh, nec faucibus odio urna ac nulla.</p> 
    <p>Maecenas laoreet in metus eget convallis. Vivamus at eleifend felis. Proin non vehicula neque. Etiam eleifend sapien ut nulla malesuada, ac condimentum nisl efficitur.</p>
  </toggle-section>
</main>

            
          
!
            
              html {
  font-family: Arial, sans-serif;
}

body {
  max-width: 40rem;
  margin: 0 auto;
  padding: 1em;
}

.controls {
 text-align: right;
 margin-bottom: 1em;
}

.controls li {
  display: inline;
}

button {
  background: #000;
  color: #fff;
  border: 0;
  font-size: 0.85rem;
  border-radius: 0.25rem;
}

/*
Custom elements are inline by default
*/
toggle-section {
  display: block;
}

/*
Only applies if script runs and 
`role="region"` is added
*/
toggle-section[role="region"] {
  border-width: 2px 0;
  border-style: solid;
}

toggle-section[role="region"] + toggle-section {
  border-top: 0;
}
            
          
!
            
              (function() {
  // Check for <template> support
  if ('content' in document.createElement('template')) {
    const tmpl = document.createElement('template')

    // Create the web component's template
    // featuring a <slot> for the Light DOM content
    tmpl.innerHTML = `
      <h2>
        <button aria-expanded="false">
          <svg aria-hidden="true" focusable="false" viewBox="0 0 10 10">
            <rect class="vert" height="8" width="2" y="1" x="4"/>
            <rect height="2" width="8" y="4" x="1"/>
          </svg>
        </button>
      </h2>
      <div class="content" hidden>
        <slot></slot>
      </div>
      <style>
        h2 {
          margin: 0;
        }

        h2 button {
          all: inherit;
          box-sizing: border-box;
          display: flex;
          justify-content: space-between;
          width: 100%;
          padding: 0.5em 0;
        }

        h2 button:focus svg {
          outline: 2px solid;
        }

        button svg {
          height: 1em;
          margin-left: 0.5em;
        }

        [aria-expanded="true"] .vert {
          display: none;
        }

        [aria-expanded] rect {
          fill: currentColor;
        }
      </style>
    `
    // Check for latest Shadow DOM syntax support
    if (document.head.attachShadow) {
      class ToggleSection extends HTMLElement {
        constructor() {
          super()

          // Make the host element a region
          this.setAttribute('role', 'region')

          // Create a `shadowRoot` and populate from template 
          this.attachShadow({ mode: 'open' })
          this.shadowRoot.appendChild(tmpl.content.cloneNode(true))

          // Assign the toggle button
          this.btn = this.shadowRoot.querySelector('h2 button')

          // Get the first element in Light DOM
          const oldHeading = this.querySelector(':first-child')
          // and cast its heading level (which should, but may not, exist)
          let level = parseInt(oldHeading.tagName.substr(1))
          // Then take its `id` (may be null)
          let id = oldHeading.id

          // Get the Shadow DOM <h2>
          this.heading = this.shadowRoot.querySelector('h2')
          
          // If `id` exists, apply it
          if (id) {
            this.heading.id = id
          }
          
          // If there is no level, there is no heading.
          // Add a warning.
          if (!level) {
            console.warn('The first element inside each <toggle-section> should be a heading of an appropriate level.')
          }
          
          // If the level is a real integer but not 2
          // set `aria-level` accordingly
          if (level && level !== 2) {
            this.heading.setAttribute('aria-level', level)
          }

          // Add the Light DOM heading label to the innerHTML of the toggle button
          // and remove the now unwanted Light DOM heading
          this.btn.innerHTML = oldHeading.textContent + this.btn.innerHTML
          oldHeading.parentNode.removeChild(oldHeading)

          // The main state switching function
          this.switchState = () => {
            let expanded = this.getAttribute('open') === 'true' || false

            // Toggle `aria-expanded`
            this.btn.setAttribute('aria-expanded', expanded)
            // Toggle the `.content` element's visibility
            this.shadowRoot.querySelector('.content').hidden = !expanded
          }

          this.btn.onclick = () => { 
            // Change the component's `open` attribute value on click
            let open = this.getAttribute('open') === 'true' || false
            this.setAttribute('open', open ? 'false' : 'true')
            
            // Update the hash if the collapsible section's 
            // heading has an `id` and we are opening, not closing
            if (this.heading.id && !open) {
              history.pushState(null, null, '#' + this.heading.id)
            }
          }
        }
        
        connectedCallback() {
          if (window.location.hash.substr(1) === this.heading.id) {
            this.setAttribute('open', 'true')
            this.btn.focus()
          } 
        }

        // Identify just the `open` attribute as an observed attribute
        static get observedAttributes() {
          return ['open']
        }

        // When `open` changes value, execute switchState()
        attributeChangedCallback(name) {
          if (name === 'open') {
            this.switchState()
          }
        }
      }

      // Add our new custom element to the window for use
      window.customElements.define('toggle-section', ToggleSection) 
    
      // Define the expand/collapse all template
      const buttons = document.createElement('div')
      buttons.innerHTML = `
        <ul class="controls" aria-label="section controls">
          <li><button id="expand">expand all</button></li>
          <li><button id="collapse">collapse all</button></li>
        </ul>
        `

      // Get the first `toggle-section` on the page
      // and all toggle sections as a node list
      const first = document.querySelector('toggle-section')
      const all = document.querySelectorAll('toggle-section')

      // Insert the button controls before the first <toggle-section>
      first.parentNode.insertBefore(buttons, first)

      // Place the click on the parent <ul>...
      buttons.addEventListener('click', (e) => {
        // ...then determine which button was the target 
        let expand = e.target.id === 'expand' ? true : false

        // Iterate over the toggle sections to switch
        // each one's state uniformly
        Array.prototype.forEach.call(all, (t) => {
          t.setAttribute('open', expand)
        })
      })
    }
  }
})()
            
          
!
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