<!-- :enabled -->
<section class="example-cntr enabled">
    <h1>CSS <code>:enabled</code> pseudo-class</h1>
    <p>All form elements are enabled by default, that is, until we add the attribute <code>disabled</code> to the element in the markup.</p>
    <p>Using a combination of <code>:enabled</code> and <code>:disabled</code> we can improve the UX with visual feedback.</p>
    <section class="notes">
        <h3>Notes:</h3>
        <ul>
            <li>Press the “Run” button on top to reset the inputs. Refresh browser too</li>
            <li>The labels turn on hover, but that’s only for demostration purposes :]</li>
        </ul>
    </section>
    <div class="flex-ctnr">
        <label class="control">
            <h4>Click to enable form elements:</h4>
            <button class="toggle"></button>
        </label>
        <div>
            <h3>Text Field</h3>
            <input type="text" disabled>
        </div>
        <div>
            <h3>Radio Button</h3>
            <input type="radio" disabled>
        </div>
        <div>
            <h3>Check Box</h3>
            <input type="checkbox" disabled>
        </div>
        <div>
            <h3>Text Area</h3>
            <textarea cols="30" rows="10" disabled></textarea>
        </div>  
    </div>    
</section>
//:enabled
.enabled > div {
    text-align: center;    
    &.flex-ctnr > div {
        flex: 1 1 auto;
        margin: 0 1%;
        padding-bottom: 30px;
        position: relative;
    }
    *[disabled] { opacity: .2; }
    .control {
        display: flex;
        flex-basis: 150px;
        align-self: center;
        align-items: center;
        height: 0;
        padding: 50px 10px;
        border: #333 1px solid;
        border-radius: 5px;
        background: linear-gradient($g,darken($g,20) 90%);
        &:hover {
            border-color: #666;
            background: darken($g,20);
        }
        h4 { margin: 0; }
        .toggle { display: none; }
    }
}

/** Rotating status bars **/

/*Variables*/
$status-bar-width: 100%;
$status-bar-height: 30px;

/* Container box to set the sides relative to */
.status-bar {
    width: $status-bar-width;
    height: $status-bar-height;    
    transition: all .2s ease;
    transform-style: preserve-3d;
    /* The lower the number the more pronounced the perspective */
    perspective: 20000px;
    /* Rotate the status bar */
    &:hover { transform: rotateX(-89deg); }
    /* Just in case you want to see the status bar rotate :) */
    &.rotate { transform: rotateX(-89deg); }
}

/* The two faces of the status-bar */
.disabled-state,
.enabled-state {
    display: flex;
    align-items: center;
    justify-content: center;
    height: $status-bar-height;
    font-size: 13px;
    color: white;
}

/* Style the sides */
.disabled-state {
    transform: translateZ($status-bar-height/2);
    background: rgba(black,.3);
}
.enabled-state {
    transform: rotateX(90deg) translateZ($status-bar-height*1.5);
    background: $g;
}

//Styling stuff not needed for demo
body { text-align: left; }
.example-cntr {
    max-width: 1200px;
    margin: auto;
    padding: 20px 50px;    
    box-shadow: 0 1px 2px rgba(black,.3);
    background: rgba(black,.15);    
}
h1 {
    text-transform: none;
    border-bottom: #636363 1px dotted;
    code {
        display: inline-block;
        margin-bottom: 10px;
        color: $y;
        background: none;
        box-shadow: none;
    }
}
code { font-size: 1em; }

input {
    display: inline-block;
    width: 30px; height: 30px;
    margin-bottom: 5px;
    vertical-align: middle;
    outline: none;
    font-size: 18px;
}
input, label { cursor: pointer; }
input[type=text],
input[type=email] { width: 100%; height: 30px; }
textarea {
    width: 100%;
    height: 50px;
}
label {
    padding: 3px 8px 5px;
    border-radius: 2px;
    border: transparent 1px solid;    
    transition: .5s;
    &:hover {
        border: rgba(white,.2) 1px solid;        
    }
}
h3 {
    font-family: Georgia;
    font-style: italic;
}
.example-cntr {
    margin-bottom: 50px;
    padding: 10px;    
    box-shadow: 0 1px 2px rgba(black,.3);
    background: rgba(black,.15);
}
.flex-ctnr {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
}
small {
    display: block;
    margin: 20px 0 10px;
    padding-top: 10px;    
    text-align: center;
}
.notes {
    display: table;
    margin: auto;
    padding: 10px 30px;
    background: rgba(lighten($y,10),.1);
}
View Compiled
//Toggle disabled/enabled attributes

//Add the labels under the fields on page load
$(".enabled input, .enabled textarea").not(".toggle").after("<div class='status-bar'> <div class='disabled-state'>Option disabled :(</div> <div class='enabled-state'>Option enabled! :}</div> </div>");

//Click the button to add classes and trigger CSS animations
$(".toggle").one("click", function(){
    //Add class .rotate to the message
    $(".status-bar").addClass("rotate");
    //Remove the attribute 'disabled'
    $(this).parents().find("input, textarea").not(".toggle").toggleAttr("disabled");
});

//toggleAttr() jQuery plugin - https://gist.github.com/mathiasbynens/298591
jQuery.fn.toggleAttr = function(attr) {
 return this.each(function() {
  var $this = $(this);
  $this.attr(attr) ? $this.removeAttr(attr) : $this.attr(attr, attr);
 });
};

External CSS

  1. https://s3-us-west-2.amazonaws.com/s.cdpn.io/9988/codepen-base_3.scss

External JavaScript

  1. //cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js