Joe Dolson

Adds a custom field to your post editing screens to add custom styles applied only on that page or post.
Attach custom styles to any page, post, or custom post type. Separate styles can be attached for print, screen, or mobile. You can also store your own library of frequently-used styles.
How to use the style library:
<ol>
<li>Add the styles you want on your settings page.</li>
<li>Navigate to an article which requires specific styles.</li>
<li>Select the library style from the drop down, leaving the style textarea blank.</li>
<li>Update or post the new document.</li>
</ol>
A newly-selected style from the style library will always overwrite any previous hand-written styles. If you wish to alter the library styles for a specific page, you can do this in the textarea after you’ve saved the page with the style library template.
By default, editing your saved stylesheets will have no impact on previously saved post-specific styles; set the option to pull styles from the library to change this.
Note: custom styles will not be included on archive pages; only on single post/Page views.
The use you’ll get out of this plugin depends on the flexibility of the theme you’re using and your own knowledge of CSS (Cascading Style Sheets).

WP Post Styling

Define custom styles for any post, page, or custom post type. Example: journal-style publications which want to create a unique design for articles.

becauseinterwebs

Tired of having to edit page templates or override theme options just to change one little thing? Tired of having to “!important” your styles?
Well, we can’t guarantee you won’t have to do that anymore 🙂 BUT, we can offer you a way to hopefully have to do LESS of it. Simply install our Custom CSS/JS plugin and you can add custom styles and scripts not only to your entire site but to individual pages and posts!
<ul>
<li>Specify javascripts and styles to use on specific pages/posts OR on a global (site wide) basis.</li>
<li>Will load external javascript references first so that you can reference them in your in-page javascripts.</li>
<li>Simple and easy to use!</li>
</ul>

Custom CSS/JS

Add custom javascripts and styles to pages and posts as well as your entire site.

WP Post Styling vs Custom CSS/JS