Pen Settings

HTML

About HTML Preprocessors

HTML preprocessors can make writing HTML more powerful or convenient. For instance, Markdown is designed to be easier to write and read for text documents and you could write a loop in Pug.

Learn more · Versions

Adding Classes

In CodePen, whatever you write in the HTML editor is what goes within the <body> tags in a basic HTML5 template. So you don't have access to higher-up elements like the <html> tag. If you want to add classes there that can affect the whole document, this is the place to do it.

About the <head>

In CodePen, whatever you write in the HTML editor is what goes within the <body> tags in a basic HTML5 template. If you need things in the <head> of the document, put that code here.

!
Insecure Resource

The resource you are linking to is using the 'http' protocol, which may not work when the browser is using https.

CSS

About CSS Preprocessors

CSS preprocessors help make authoring CSS easier. All of them offer things like variables and mixins to provide convenient abstractions.

Learn more · Versions

CSS Base

About CSS Base

It's a common practice to apply CSS to a page that styles elements such that they are consistent across all browsers. We offer two of the most popular choices: normalize.css and a reset. Or, choose Neither and nothing will be applied.

Vendor Prefixing

About Vendor Prefixing

To get the best cross-browser support, it is a common practice to apply vendor prefixes to CSS properties and values that require them to work. For instance -webkit- or -moz-.

We offer two popular choices: Autoprefixer (which processes your CSS server-side) and -prefix-free (which applies prefixes via a script, client-side).

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.

Powered by Algolia
About External Resources

You can apply CSS to your Pen from any stylesheet on the web. Just put a URL to it here and we'll apply it, in the order you have them, before the CSS in the Pen itself.

You can also link to another Pen here (use the .css URL Extension) and we'll pull the CSS from that Pen and include it. If it's using a matching preprocessor, use the appropriate URL Extension and we'll combine the code before preprocessing, so you can use the linked Pen as a true dependency.

Learn more

+ add another resource

JavaScript

About JavaScript Preprocessors

JavaScript preprocessors can help make authoring JavaScript easier and more convenient.

Learn more · Versions

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.

Powered by Algolia
About External Resources

You can apply a script from anywhere on the web to your Pen. Just put a URL to it here and we'll add it, in the order you have them, before the JavaScript in the Pen itself.

If the script you link to has the file extension of a preprocessor, we'll attempt to process it before applying.

You can also link to another Pen here, and we'll pull the JavaScript from that Pen and include it. If it's using a matching preprocessor, we'll combine the code before preprocessing, so you can use the linked Pen as a true dependency.

Learn more

+ add another resource

Packages

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.

Powered by Algolia
About Packages

Using packages here is powered by Skypack, which makes packages from npm not only available on a CDN, but prepares them for native JavaScript ES6 import usage.

All packages are different, so refer to their docs for how they work.

If you're using React / ReactDOM, make sure to turn on Babel for the JSX processing.

Behavior

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.

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.

HTML 

              
                <input type="checkbox" id="nav">
<a id="close" href="#open"><span class="sr-only">Close Menu</span></a>
<a id="open"  href="#close"><span class="sr-only">Open Menu</span></a>
<header>
  <h1><a href="#home">Toggle Menu w/ Focus-Trap</a></h1>
  <label for="nav">
    <span>Menu</span>
    <span>Dismiss</span>
  </label>
  <nav>
    <a href="#item1">Item One</a>
    <a href="#item2">Item Two</a>
    <a href="#item3">Item Three</a>
    <a href="#item4">Item Four</a>
  </nav>
</header>
<main>
  <h2>An Update of Apple's CSS Menu with Focus Trapping and Autofocus</h2>
  <p>This menu is built upon the ideas of Apple's responsive menu <a id="item1" href="https://developer.apple.com/design/human-interface-guidelines/">here</a>, stripped down without extras like CSS animation.</p>
  <p>It has the following change and - I hope - improvement:</p>
  <ol>
    <li>Toggling between the open and close anchor tag will autofocus between them.</li>
    <li>Content will be hidden when menu is open, preventing content being focused.</li>
  </ol>
  <h3>Trap Focus by Removing Content</h3>
  <p>Without JavaScript, the ideal solution to trap focus would have been the ill-fated <code>nav-index</code> CSS property, alas it's gone.</p>
  <p>So the only other solution is to remove everything else so there's nothing <i>to</i> focus beside the menu.</p>
  <p>Doing this is disorienting for the user though.</p>
  <h3>Tab Order Issue</h3>
  <p>Because the anchors needs to auto-focus (set :target to self) and also set <code>display</code> property for contents, it means the anchor tag must live on the same level as the content elements. This makes the HTML structure a bit weird. The anchor tag must live outside of the header, and because it must alter label state it needs to be placed ahead of the header.</p>
  <p>Unfortunately, this means the anchor tags is placed ahead of the header for tab order, creating confusion if you have any other focusable element in the header besides the menu, a hyperlinked logo, for instance.</p>
  <p>You'd think it can be solved with <code>taborder</code>, but because the default tab order is 0 and negative value removes it from tab order, you cannot selectively place an element ahead of everything else - there's nothing between 0 and negative, a gross oversight in my opinion.</p>
  <p>Of course you can do the opposite, but adding tabindex for every other focusable element on the entire page is an unfeasible proposition.</p>
  <p>So for me the solution as it currently stands is not optimal, I will probably revisit it.</p>
  <a href="#">Focus Test 1</a>
  <p></p>
</main>
<aside>
  <h2>Behaviour</h2>
  <p>Trap focus by removing content while mobile menu is open.</p>
  <a href="#">Focus Test 2</a>
</aside>
<footer>
  Footer
</footer>
!

CSS 

              
                /* 100% height */
html {
    height:100%;
    display: flex;
    flex-direction:column;
}
body {
    width:100%;
    flex-grow:1;
    flex-basis:0;
}
html, body {margin:0;padding:0;}

/* color scheme */
:root {
  --clr-header: #ae92f5;
  --clr-body: #f5f2fb;
  --clr-side: #e0daee;
  --clr-footer: #ae92f5;
  --clr-btn: #4a3ca1;
  --clr-btn-hover: #6353c3;
  --clr-btn-txt: #d1c3f5;
  --clr-btn-txt-hover: white;
  --clr-btn-border: #6e5fcb;
  --clr-body-txt: #2f2c35;
}

body > * {padding: 1rem}
h1 {font-size: 1.4rem; margin:0}
h2 {font-size: 1.2rem}
h3 {font-size: 1.1rem;}

/* pull up menu */
body {
  display:grid;
  grid-template-areas: 
    "header header"
    "main   aside"
    "footer footer";
  grid-template-rows:  auto 1fr auto;
  grid-template-columns: 2fr 1fr;
  font-family: sans-serif;
  color: var(--clr-body-txt);
}

header {grid-area:header; background:var(--clr-header)}
main   {grid-area:main;   background:var(--clr-body)}
aside  {grid-area:aside;  background:var(--clr-side)}
footer {grid-area:footer; background:var(--clr-footer)}

header {
  display:flex;
  flex-wrap:wrap;
  align-items:center;
  justify-content:space-between;
  gap:1rem;
}
h1 a {color:var(--clr-body-txt)}
nav {
  display:flex;
  flex-wrap:wrap;
  justify-content:flex-end;
  gap:.5rem .75rem
}
nav a {
  padding:.3rem .6rem;
  background:var(--clr-btn);
  color: var(--clr-btn-txt);
  text-decoration:none;
  border-radius:.4rem;
}
nav a:hover,
nav a:active,
header label:hover span,
header label:active span  {
  background:var(--clr-btn-hover);
  color:var(--clr-btn-txt-hover);
}

#open,
#close,
input#nav,
header label {display:none}

@media (max-width: 768px) {
  body {
    grid-template-areas: 
      "header toggle"
      "nav nav"
      "main main"
      "aside aside"
      "footer footer";
    grid-template-columns: 1fr auto;
    grid-template-rows: auto auto 1fr;
  }
  /* open up header */
  header {display:contents}
  /* use overlapping pseudo element for background */
  header:before {
    content:"";
    grid-column:header/toggle;
    grid-row:header;
    background:var(--clr-header);
  }
  h1 {
    grid-area:header;
    padding:1rem;
    display:flex;
    align-items:center;
    justify-content:space-between;
    gap:1rem;
  }
  /* keep toggle label span the same size */
  #open,
  #close {
    display:initial;
    grid-area:toggle;
    pointer-events: none;
    cursor: default;
    z-index:1
  }
  .sr-only {
    position:absolute;
    clip-path:inset(0px 0px 99.9% 99.9%);
    overflow:hidden;
    height:1px;
    width:1px;
    padding:0;
    border:0
  }
  header label {
    grid-area:toggle;
    display:grid;
    grid-template-areas:"label";
    font-family:sans-serif;
    font-weight:bold;
    color:white;cursor:pointer;
    user-select:none;
    margin:.5rem 1rem;
  }
  header label span {
    grid-area:label;
    text-align:center;
    background: var(--clr-btn);
    padding: .5rem;
    border-radius:.5rem;
    align-self:center;
    color:var(--clr-btn-txt)
  }
  /* vertical menu styling */
  nav {
    grid-area:nav;
    flex-direction:column;
    gap:0;
    display:none;
  }
  nav a {
    padding:.75rem 1rem;
    border-radius:0
  }
  nav a:not(:last-child) {
    border-bottom:1px solid var(--clr-btn-border);
  }
  /* prevent outline from being cut off */
  #open:focus,
  #close:focus,
  nav a:focus {
    outline-offset:-2px;
  }
  /* toggle logic */
  #nav:checked + header nav,
  #close:target ~ nav {display:flex}

  #close:target ~ header nav,
  #nav:checked ~ header nav {
    grid-area:nav / main / aside / footer;
    justify-content:flex-start;
   background:var(--clr-btn);
   display:flex;
   z-index:1;
  }
  #close:target ~ header ~ * ,
  #nav:checked ~ header ~ * {display:none;}
  
  /* label toggle */
  #nav:not(:checked) ~ header label :last-child  {visibility:hidden}
  #nav:checked ~ header label :first-child {visibility:hidden}
  /* anchor toggle */
  #close,
  #close:target + #open {display:none}
  #close:target {display:initial}
  #close:target ~ header label span:first-child {visibility:hidden}
  #close:target ~ header label span:last-child {visibility:visible}
}
!

JS
!
999px

Console