George Stephanis

This plugin re-adds a standalone editing page for Custom CSS 
in the WordPress Admin UI, for users that aren’t comfortable 
using the one in the Customizer.
Currently it only works with Jetpack and Jetpack’s added features, 
but shortly it will work without Jetpack as well, providing a 
more basic text editor without syntax highlighting.

Legacy Jetpack Custom CSS Editor

I was utterly dismayed to see the old Jetpack CSS editor disappear in favor of a little customizer box in WP 4.7. Thank you so much for restoring the legacy editor where we can actually see what we're working with, and where our designer can work with CSS without having to upload style.css every time they make a change. It's a vital part of our workflow and the little box in the customizer is completely inadequate.

many thanks for this lifesaver

This plugin re-adds the full page admin Custom CSS editor to Jetpack.

wpwox

This plugin provides custom meta boxes in default Pages and Posts of wordpress where you can enter any scripts for each respective pages or posts, for example:
<ol>
<li>Google Adwords conversion tracking</li>
<li>Google Adsense ads</li>
<li>Any Javascripts</li>
<li>Page/post specific CSS codes</li>
<li>Normal HTML codes</li>
<li>Unlimited possibilites</li>
</ol>
You will get a meta box under each of page and post. The Meta box will have 4 Text Boxes, in each section you can add codes for:
<ol>
<li>Before Content Field</li>
<li>Below Content Field</li>
<li>Scripts to add in tag</li>
<li>Scripts to add in footer below tag</li>
</ol>
Plugin Documentation: 
http://www.wpwox.com/wp-plugin/custom-script-integration/

Custom Script Integration

This plugin provides custom meta box to add Google Adword conversion, ads, custom css and scripts in individual pages/posts.

Legacy Jetpack Custom CSS Editor vs Custom Script Integration