The remaining elements for Isotope filters you will need

CSS

/**** Isotope Filtering ****/

.isotope-item {
  z-index: 2;
}

.isotope-hidden.isotope-item {
  pointer-events: none;
  z-index: 1;
}

/**** Isotope CSS3 transitions ****/

.isotope,
.isotope .isotope-item {
  -webkit-transition-duration: 0.8s;
     -moz-transition-duration: 0.8s;
      -ms-transition-duration: 0.8s;
       -o-transition-duration: 0.8s;
          transition-duration: 0.8s;
}

.isotope {
  -webkit-transition-property: height, width;
     -moz-transition-property: height, width;
      -ms-transition-property: height, width;
       -o-transition-property: height, width;
          transition-property: height, width;
}

.isotope .isotope-item {
  -webkit-transition-property: -webkit-transform, opacity;
     -moz-transition-property:    -moz-transform, opacity;
      -ms-transition-property:     -ms-transform, opacity;
       -o-transition-property:      -o-transform, opacity;
          transition-property:         transform, opacity;
}

/**** disabling Isotope CSS3 transitions ****/

.isotope.no-transition,
.isotope.no-transition .isotope-item,
.isotope .isotope-item.no-transition {
  -webkit-transition-duration: 0s;
     -moz-transition-duration: 0s;
      -ms-transition-duration: 0s;
       -o-transition-duration: 0s;
          transition-duration: 0s;
}

Filter-Nav

// Katrina, you will need to add this to the top of your page.

<ul id="filters" class="option-set">
    <li><a class="selected" href="#" data-filter="*">All</a></li><?php // leaving a line break after this <li> tag results in a faux margin
    $args = array(
        'orderby' => 'name',
        'parent' => 0
    );
    $categories = get_categories( $args );
    foreach ( $categories as $category ) {
        echo '<li><a href="#" data-filter=".'.$category->category_nicename.'">' . $category->name . '</a></li>';
    }
?>
</ul>



// In addition, you will need to add this to the loop of your idividual isotope items.

// After the loop begins, add this declaration inside the php...

    $category = get_the_category();
    

// Now, inside the "class" for the isotope items, you need to add this: <?php echo $category[0]->category_nicename; ?> So, it should look something like this...

<div class="box isotope-item <?php echo $category[0]->category_nicename; ?>">

jQuery

        
        
        // Filter items when filter link is clicked
        $('#filters a').click(function(){
          var selector = $(this).attr('data-filter');
          $container.isotope({ filter: selector });
          return false;
        });

        // Add class based on selection
        var $optionSets = $('#filters.option-set'),
            $optionLinks = $optionSets.find('a');

            $optionLinks.click(function(){
            var $this = $(this);
            // don't proceed if already selected
            if ( $this.hasClass('selected') ) {
              return false;
            }
            var $optionSet = $this.parents('.option-set');
            $optionSet.find('.selected').removeClass('selected');
            $this.addClass('selected');
        
            // make option object dynamically, i.e. { filter: '.my-filter-class' }
            var options = {},
                key = $optionSet.attr('data-option-key'),
                value = $this.attr('data-option-value');
            // parse 'false' as false boolean
            value = value === 'false' ? false : value;
            options[ key ] = value;
            if ( key === 'layoutMode' && typeof changeLayoutMode === 'function' ) {
              // changes in layout modes need extra logic
              changeLayoutMode( $this, options )
            } else {
              // otherwise, apply new options
              $container.isotope( options );
            }
            
            return false;
        });