Ben Huson

<h4>Add missing classes</h4>
Adds missing classes for selected menu states. Classes added include:
<ul>
<li><code>current-page-parent</code> and <code>current_page_parent</code></li>
<li><code>current-page-ancestor</code> and <code>current_page_ancestor</code></li>
<li><code>current-menu-ancestor</code></li>
<li><code>current-menu-parent</code></li>
</ul>
The classes are added in the following scenarios:
<ul>
<li>When viewing an attachment page classes are added to any parent pages and their menu ancestors.</li>
<li>When viewing a post classes are added to any relevant taxonomy menu items and their manu ancestors.</li>
</ul>
<h4>Manage Menu Select States</h4>
Allows you to control which menu items should be selected (or deselected) when viewing certain pages of your site. You need to add classes to the menu items for this to work.
<ul>
<li><code>ecms-archive-{$post_type}</code> – Select menu item when viewing a post type archive page.</li>
<li><code>ecms-single-{$post_type}</code> – Select menu item when viewing a single post type page.</li>
<li><code>ecms-taxonomy-{$taxonomy}</code> – Select menu item when viewing a taxonomy archive.</li>
<li><code>ecms-taxonomy-{$taxonomy}-term-{$term}</code> – Select menu item when viewing a taxonomy term archive.</li>
<li>
<code>ecms-404</code> – Select menu item when viewing a 404 page.
</li>
<li>
<code>ecms-no-archive-{$post_type}</code> – Deselect menu item when viewing a post type archive page.
</li>
<li><code>ecms-no-single-{$post_type}</code> – Deselect menu item when viewing a single post type page.</li>
<li><code>ecms-no-taxonomy-{$taxonomy}</code> – Deselect menu item when viewing a taxonomy archive.</li>
<li><code>ecms-no-taxonomy-{$taxonomy}-term-{$term}</code> – Deselect menu item when viewing a taxonomy term archive.</li>
<li><code>ecms-no-404</code> – Deselect menu item when viewing a 404 page.</li>
</ul>

Extra Classes

Adds classes for selected menu states such as highlighting categories when viewing a blog post or parent page when viewing an attachment page.

nivijah

This simple plugin adds two additional fields to the media window, that lets you set additional classes to images on top of the default ones.
After installation two fields will be added to the media window under an image, One for custom class for featured image, and the other for images who are added into the WordPress editor.
Multiple class should be seperated by “space”.

Custom CSS classes for images

This simple plugin adds two additional fields to the media window, that lets you set additional classes to images on top of the default ones.

Extra Classes vs Custom CSS classes for images