TylerShaw

What’s It Do?
This plugin adds a box to your pages and posts allowing for page-specific or post-specific CSS stylesheets.
Why Use It?
After developing quite a few WordPress websites, it seems to me that the style.css file gets bloated. If you add a style used on only one page, and then later that page is deleted, you’re visitors now have to download those styles that aren’t even used. It’s wasteful, but maintaining a clean style.css file requires an active effort. This plugin solves that by attaching the these styles to the page or post, allowing them to be updated just like the content is and deleted with the page.
It keeps your style.css file clean and reduces unused style clutter.
What About Efficiency?
There shouldn’t be an issue with overhead from the plugin. Admin code is only executed in the admin panel and front end code is executed on the front end. If you’re website has a large amount of page-specific styles within it that can be migrated into the plugin, it can boost performance by reducing the download size of your style.css file.
Roadmap
This plugin will receive ongoing maintenance as WordPress evolves. No major features are planned, but I am entirely open to feature requests!
Feel free to suggest any feature you desire, or check out the code or contribute on <a href="https://github.com/tyler-shaw/page-specific-stylesheets" rel="nofollow ugc">GitHub</a>, where the project is hosted.
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<li>Additional plugin options.</li>
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If you have a feature idea, suggest it.
Notes
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<li>Style data and options are not deleted by default on uninstall. You must check the options on the plugin settings page to enable the deletion of this data.</li>
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Page Specific Stylesheets

Adds a box allowing for the addition of page-specifc and post-specific CSS stylesheets. Reduces the need to edit and clutter up the style.css file.

Łukasz Nowicki

Post/Page/Product-specific custom code allows you to add custom CSS styles to individual posts, pages, or WooCommerce products. It provides a dedicated area in the editor screen where you can write your CSS code. You can also choose whether the CSS should apply only to the single view or also to archive-type views.
A new meta box will appear below the content editor on the edit screen for posts, pages, and products. You can enter any custom CSS there and decide whether it loads only on the single view or also on archive pages like category listings or product grids.
<h3>Requirements</h3>
This plugin requires at least WordPress 5.0 (remember always to keep your WordPress installation up to date!) and PHP 7.4 on your server.

Post/Page Specific Custom Code

Great plugin!

A very useful plugin

Add custom CSS to posts, pages, or WooCommerce products, with optional archive support. Includes a dedicated editor box.

Page Specific Stylesheets vs Post/Page Specific Custom Code