<div class="example-cntr backdrop">
    <h1>CSS <code>::backdrop</code> pseudo-element</h1>
    <p>The <code>::backdrop</code> pseudo-element is a box that the full screen element has behind it, but at the same time it sits above all other content.</p>
    <p>It can be used together with the <code>:fullscreen</code> pseudo-class or the <code>&lt;dialog></code> HTML5 element to change the background color of the maximized screen, just in case we don’t want to go with the default black.</p>
    <div class="notes">
        <h2>A few notes to consider:</h2>
        <ol>
            <li>It’s mandatory to use double colon with the <code>::backdrop</code> pseudo- element, it doesn’t work with single colon like with other pseudo-elements.</li>
            <li>Edge is the only one that shows any styling of the <code>::backdrop</code> pseudo-element in this demo.</li>
            <li>Firefox 47 (<a href="https://developer.mozilla.org/en-US/Firefox/Releases/47" target="_blank" title="Links opens in a new tab">release date June 29, 2016</a>) will start supporting the <code>::backdrop</code> pseudo-element.</li>
            <li>Also, <a href="http://caniuse.com/#search=dialog" target="_blank"
                    title="Links opens in a new tab">no current version of Firefox supports the <code>&lt;dialog></code></a> HTML5 element.</li>
            <li>Chrome doesn’t style the <code>::backdrop</code> pseudo-element when used with the <code>:fullscreen</code> pseudo-class even though <a href="https://developer.mozilla.org/en-US/docs/Web/CSS/::backdrop#Browser_compatibility" target="_blank"
                    title="Links opens in a new tab">MDN states that Chrome does support it </a>if prefixed with <code>-webkit-</code>. This is for Example 1.</li>
            <li>Chrome properly styles the <code>::backdrop</code> pseudo-element when used with the <code>&lt;dialog></code> HTML5 element. This is for Example 2.</li>
            <li><a href="http://caniuse.com/#search=dialog" target="_blank"
                    title="Links opens in a new tab">Only Chrome supports the <code>&lt;dialog></code></a> HTML5 element at the moment.</li>            
            <li>No mobile device supports the <code>::backdrop</code> pseudo-element.</li>
        </ol>
    </div>
    <div class="example">
        <h2>Example 1: Using <code>:fullscreen</code></h2>
        <h1 id="element"><span class="hide">The text is injected via CSS</span></h1>
        <button onclick="var el = document.getElementById('element'); el.webkitRequestFullscreen();">Trigger Full Screen!</button>
    </div>
    <div class="example">
        <h2>Example 2: Using <code>&lt;dialog></code></h2>
        <dialog>
            <h1>This is a dialog. Good job! :]</h1>
            <p>Press <code>ESC</code> or click on Close button.</p>
            <hr>
            <button id="close">Close</button>
        </dialog>
        <button id="show">Open Dialog!</button>
    </div>
</div>

//Example 1
#element {
    border-bottom: none;
    background: none;
    //Content in "normal" mode.
    &:before {
        content: 'Normal mode';
    }
    //Content in fullscreen mode
     &:fullscreen:before {
         content: 'Fullscreen mode';         
    }    
    &:fullscreen::backdrop {
        background: $b;
    }
    //According to MDN we need to prefix, but it doesn't work in my tests.
    &:fullscreen::-webkit-backdrop {
        background: $b;
    }
}

//Example 2
dialog {
    width: 350px;
    padding: 40px;
    border: 1px solid rgba(black,.3);
    border-radius: 2px;
    box-shadow: 0 5px 20px black;
    top: 30%;
}
dialog::backdrop {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(darken($g,25),.8);
}





//Styling stuff not needed for demo
body {
    text-align: left;
    line-height: 1.5;
}
h1 {
    font-size: 22px;
    text-transform: none;
    border-bottom: #636363 1px dotted;
    code {
        display: inline-block;
        margin-bottom: 10px;
        color: $y;
        background: none;
        box-shadow: none;
    }
}
h2 { font-size: 18px; }
code { font-size: 1em; }
.example-cntr {
    max-width: 800px;
    margin: 0 auto 50px;
    padding: 30px;
    box-shadow: 0 1px 2px rgba(black,.3);
    background: rgba(black,.15);
    & > code {
        display: block;
        margin-bottom: 10px;
        font-size: 22px;
        color: $y;
        background: none;
        box-shadow: none;
    }
}
.underline { text-decoration: underline; }

//
.hide { display: none; }
#element {
    border-bottom: #444 1px solid;
    padding-bottom: 20px;
    &:before { 
        display: block;
        padding: 5px 0;
        background: $g;
    }
    &:fullscreen:before {
        display: block;
        padding: 5px 250px;
        background: $r;
    }    
}
button {
    padding: 8px 15px;
    cursor: pointer;
    background: linear-gradient(white, #aaa);
    border-radius: 2px;
    &:hover { background: white; }
    &:active { background: linear-gradient(#aaa, white 20%);}
}
.note {
    color: desaturate($y,30);
    font-size: 12px;
    letter-spacing: .5px;
}
.notes {
    margin-bottom: 20px;
    padding: 20px 20px 0;
    border: #444 1px solid;
    border-radius: 3px;
    h2 { margin: 0; }
}
.example {
    margin: 0 20px;
    padding: 20px;
    background: rgba(black,.2);
    margin-bottom: 20px;
    &:last-child { margin-bottom: 0; }
    h1 { border: none !important; margin-bottom: 0 !important; }
    h2 { margin-top: 0; }
}
dialog {
    text-align: center;
    p { text-align: left; }
}

//Trigger the dialog box
var dialog = document.querySelector('dialog');
document.querySelector('#show').onclick = function() {
  dialog.showModal();
};
document.querySelector('#close').onclick = function() {
  dialog.close();
};

/* More information about the <dialog> element here: http://demo.agektmr.com/dialog/  */