A CodePen by Andrew Maxwell.

index.html

<div class="fake_background">
    <!-- Editable Dropdown -->
    <div id="kind">
        <div id="current_selection" class="kind_selection">:nth-child</div>
        <div id="kind_arrow" class="selection_arrows">
            <span class="top_arrow">▲</span>
            <span class="bottom_arrow">▼</span>
        </div>
        <ul id="kind_options" class="selection_options">
            <li data-value=":nth-child" class="selected">:nth-child</li>
            <li data-value=":nth-of-type">:nth-of-type</li>
            <li data-value=":nth-last-child">:nth-last-child</li>
            <li data-value=":nth-last-of-type">:nth-last-of-type</li>
        </ul>
    </div>
  
  
    <select id="old">
        <option value=":nth-child" selected="">:nth-child</option>
        <option value=":nth-of-type">:nth-of-type</option>
        <option value=":nth-last-child">:nth-last-child</option>
        <option value=":nth-last-of-type">:nth-last-of-type</option>
    </select>
</div>

script.js

var menu = {
    init : function() {
        menu.toggleDropdown();
        menu.optionSelection();
      
      $('.fake_background').on('click', function() {
          menu.removeSelection();  
      });
    },
    
    
    toggleDropdown : function() {
       $('#current_selection').on('click', function(event) {
            event.stopPropagation();   
            var selectionContainer = $('#kind_options');
            selectionContainer.toggleClass('visible');
        });
      
      $('#kind_arrow').on('click', function(event) {
            event.stopPropagation();   
            var selectionContainer = $('#kind_options');
            selectionContainer.toggleClass('visible');
        });
    },
  
  removeSelection : function() {
      var selectionContainer = $('#kind_options');
      selectionContainer.removeClass('visible');
  },

    optionSelection : function() {
        var kindOption = $('#kind_options').find('li');
        kindOption.on('click', function(event) {
            event.stopPropagation();
          
            // Remove selection from all items
            kindOption.removeClass('selected');

            $(this).addClass('selected');
            
            
            var alertMe = function( data ) {
                //alert( data );
            };
            menu.changeSelection( alertMe );
            menu.removeSelection();
        });
    },

    changeSelection : function( callback ) {
        // Get the selected value and display that and the current selection
        var selectedItem = $('#kind_options').find('li.selected');
        var selectedItemText = selectedItem.text();
        var selectionContainer = $('#current_selection');

        selectionContainer.text(selectedItemText);
      
        if( callback ) {
            callback(selectedItem.attr('data-value'));
        }
    }
};
  

menu.init();

style.scss

@import "compass";
.fake_background {
    background: url(http://css-tricks.com/wp-content/themes/CSS-Tricks-10/images/bg.png);
    box-shadow: inset 0 0 15px rgba(0,0,0,.7);
    float: left;
    height: 400px;
    margin: 40px;
    width: 400px;  
}
#kind {
    background: #FFF;
    border: 0;
    border-radius: 5px;
    float: left;
    font: inherit;
    font-size: 15px;
    height: 20px;
    margin: 60px 0 0 90px;
    padding: 4px;
    position: relative;
    width: 200px;
}

.kind_selection {
   cursor: pointer;
   padding: 2px 0 0 5px;
}

.selection_arrows {
    border-left: solid 1px #CCC;
    border-radius: 0 5px 5px 0;
    cursor: pointer;
    height: 28px;
    position: absolute;
    right: 0;
    top: 0;
    width: 20px; 
}

.top_arrow {
    color: #333;
    display: block;
    float: left;
   font-size: 7px;
   margin: 5px 0 0 6px;
}

.bottom_arrow {
    color: #333;
    display: block;
    float: left;
   font-size: 7px;
   margin: 1px 0 0 6px;
}

.selection_options {
    background: #FFF;
    border-radius: 5px;
    box-shadow: 2px 2px 3px 0 rgba(0, 0, 0, .5);
    display: none;
    left: 0;
    list-style-type: none; 
    margin: 0;
    padding: 0;
    position: absolute;
    top: 28px;
    width: 207px;
}

.selection_options li {
    cursor: pointer;
    margin: 0;
    padding: 5px 30px;
    position: relative;
  
    &:hover {
        background: blue;
        color: #FFF;
    }
  
    &:first-child {
          border-radius: 4px 4px 0 0;
    }
    
    &:last-child {
        border-radius: 0 0 4px 4px;
    }
  
   &.selected {
      background: #BADA55;
    
      &:before {
        content: '✓';
        left: 10px;
        position: absolute;
      }
    }
}

.visible {
   display: block; 
}

#old {
    float: left;
    font-size: 17px;
    height: 40px;
    margin: 60px 0 0 90px;
    width: 210px;
}