Cernocky

The Custom Post Styles plugin is an easy way to customize css of your posts individualy using CSS code. 
Plugin adds css editor box in your post editor.
See it in action: 
https://vimeo.com/179525212
Improve the user experience for your readers without having to change theme code.
<h4>Possible upcoming features</h4>
<ul>
<li>Better CSS editor</li>
<li>Custom webfonts</li>
<li>Supporting more post types</li>
<li>Custom styles for posts by categories, authors etc.</li>
<li>Visual editor</li>
</ul>

Custom Post Styles

Allows you to add custom css styles to posts.

Melissa Cabral

A simple, lightweight plugin that displays useful technical information on pages and posts to aid in developing WordPress Classic themes. Provides quick access to things that are sometimes hidden, like post/page ID, slug, taxonomy terms, and post type slug. Theme Inspector tells you exactly what conditional tags are true on each view, and what template file loaded on each page view.
<ul>
<li>Use In Conjunction with the <a href="https://docs.google.com/drawings/d/1hJ0MpHO3HKBT5KsTpGtc_gDYZ5pi-HyxNcRtmPBBULE" rel="nofollow ugc">WP Template Hierarchy Document</a>.</li>
<li>Theme Inspector is only visible to logged in Administrators.</li>
<li>Appears on the right-side of the Toolbar (admin bar).</li>
</ul>

Theme Inspector

A developer's inspector to illuminate the WordPress Template Hierarchy and help with building WordPress Classic themes.

Custom Post Styles vs Theme Inspector