Justin Tadlock

<p>The Custom Classes plugin allows you to create custom classes for posts (when <code>post_class()</code> is called) and for the <code><body></code> class (when <code>body_class()</code> is called).  It creates a meta box on the edit post and edit term screens in the admin with input boxes for adding your custom classes.</p>
<p>Custom post classes are added whenever your theme calls the <code>post_class()</code> function, which is generally whenever a post is shown.  Custom body classes are added on the single view of the post whenever your theme calls the <code>body_class()</code> function.</p>
<h3>Like this plugin?</h3>
<p>Please consider helping the cause by:</p>
<ul>
<li><a href="https://themehybrid.com/donate" rel="nofollow ugc">Making a donation</a>.</li>
<li><a href="https://themehybrid.com/club" rel="nofollow ugc">Signing up at my site</a>.</li>
<li><a href="https://wordpress.org/support/view/plugin-reviews/custom-classes?rate=5#postform" rel="ugc">Rating the plugin</a>.</li>
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<h3>Professional Support</h3>
<p>If you need professional plugin support from me, the plugin author, you can access the support forums at <a href="https://themehybrid.com/board/topics" rel="nofollow ugc">Theme Hybrid</a>, which is a professional WordPress help/support site where I handle support for all my plugins and themes for a community of 75,000+ users (and growing).</p>
<h3>Plugin Development</h3>
<p>If you’re a theme author, plugin author, or just a code hobbyist, you can follow the development of this plugin on it’s <a href="https://github.com/justintadlock/custom-classes" rel="nofollow ugc">GitHub repository</a>.</p>
<h3>Will this work with custom post types?</h3>
<p>Certainly.  This plugin works with any public post type on your site.  It’s not just limited to the “post” post type.</p>
<h3>It’s not working!</h3>
<p>Most likely, this means your theme isn’t using the appropriate functions (<code>post_class()</code> and <code>body_class()</code>).  You’ll need to talk to your theme author to get them to fix this.  Or, better yet, use a correctly-coded theme from <a href="https://themehybrid.com/themes" rel="nofollow ugc">Theme Hybrid</a>!</p>


Custom Classes

If all you need is to add custom classes to body on a per page / post basis, this plugin is all you need.

Works nicely!

Allows users to create custom classes on a per-post/term basis.

santerref

<p>This plugin adds a new setting in the media gallery settings to set a custom CSS class.</p>
<p>The shortcode is updated with a new attribute “class”. A function alters the output of the gallery and wrap it with a new div with your custom class and the class “gallery-wrapper”.</p>


Gallery Class

Gallery Class adds a new setting in the media gallery settings to set a custom CSS class.

Custom Classes vs Gallery Class