keegnotrub

An update on the incredible Art Direction plugin by Noël Jackson (http://noel.io) and Dave Rupert (http://daverupert.com). Allows you to enter custom CSS to be applied per post/page.
Additional features include:
<ul>
<li>Optionally place span classes on your post/page title characters </li>
<li>Optionally place span classes on your post/page title words</li>
<li>Ability to responsivley use viewport units on post/page title</li>
</ul>

Artsy

Art Direction for WordPress - Allows you to enter custom CSS to be applied per post/page.

José Marques

Sometimes you need some extra styling and TinyMCE does not allow a lot. 
This plugin allows you to add per post or page CSS and Javascript.

Content Art Direction

Allows custom styling and interaction for posts and pages

Artsy vs Content Art Direction