Theme Junkie

This plugin will enable a <a href="https://www.theme-junkie.com/plugins/theme-junkie-custom-css/" rel="nofollow ugc">custom css manager</a> on administration page to add Custom CSS code to your WordPress website. It will automatically override any theme or plugin default styles. It also very useful if you want to add customization to your website but do not want to edit your theme or plugin css files.
It comes with two ways to add the custom css code:
1. Setting 
You can go to Appearance → Custom CSS, then you will see a big box/textarea. Put your css code there.
2. Customizer – Live Preview 
If you want to see the live preview while you adding the custom css code, then you can go to Appearance → Customize, after that open the Custom CSS section tab.
<h4>Features Include:</h4>
<ul>
<li>No configuration needed</li>
<li>Live preview</li>
<li>Easy-to-use</li>
<li>Child theme alternative to add customization</li>
<li>Uninstall procedure</li>
</ul>
<h4>Plugin Info</h4>
<ul>
<li>Developed by <a href="https://www.theme-junkie.com/?utm_source=wporg&utm_medium=text_link&utm_campaign=Site%20Promotion" rel="nofollow ugc">Theme Junkie</a></li>
<li>Check out the <a href="https://github.com/themejunkie/theme-junkie-custom-css" rel="nofollow ugc">Github</a> repo to contribute.</li>
</ul>

TJ Custom CSS

Simply works

Easily to add any Custom CSS code to your WordPress website.

SilkyPress

Customize your WordPress site’s appearance by easily adding custom CSS and JS code without even having to modify your theme or plugin files. This is perfect for adding custom CSS tweaks to your site.
<h4>Features</h4>
<ul>
<li>Text editor with syntax highlighting </li>
<li>Print the code inline or included into an external file</li>
<li>Print the code in the header or the footer</li>
<li>Add CSS or JS to the frontend or the admin side</li>
<li>Add as many codes as you want</li>
<li>Keep your changes also when you change the theme</li>
</ul>

Simple Custom CSS and JS


When saving CSS as external file, I'm disappointed that you can't name the css file, you can change the permalink and then a duplicate CSS file is created with the name but it is still not used by this plugin.It is much better than Jetpack's version which is horrible.



I have now stopped using it as it also forces you to load the CSS where I needed to conditionally include it, I am now using a text editor, FTP, and wp_enqueue_style() in a child functions.php.  Much easier (at least after working it out), the below code added before the html header started (not sure if that matters):



//===========================================================================
function CompanyHeaderAssets()
//===========================================================================
{
    //--- Main Company CSS ------------------------------------------------
    $CssDir  = '/wp-content/themes/oceanwp-child-theme-master/';
    $CssName = 'Company CSS for Dynamic Pages.css';
    wp_enqueue_style("CompanyCss4All", "{$CssDir}{$CssName}", '', time());

    //--- Main Company CSS 4 ADMINS ---------------------------------------
    if  (IsCompanyVolunteer())
    {
        //--- Not displaying to visitors ------------------------------------
        $CssName = 'Company CSS for Image Gallery Metadata Tooltips (Volunteers Only).css';
        wp_enqueue_style("CompanyCss4StaffOnly4ImageMetadata", "{$CssDir}{$CssName}", '', time());
    }
}
add_action( 'wp_enqueue_scripts', 'CompanyHeaderAssets' );


Good Except Can't Name Files (4567.css etc)


This is a nice handy plugin, but it seems to not load CSS on Elementor pages for some reason. Otherwise nice plugin.


Handy plugin but...


This plugin does flush all permalinks settings on install, without confirmation of Admin, which impacted the whole permalinks settings, and required me to deactivate and reactivate multiple plugins to get their permalinks settings setup again, which is loss of time and requires a clear confirmation before doing that on install.


Impacted the permalinks

Just what I was looking for

Easily add Custom CSS or JS to your website with an awesome editor.

TJ Custom CSS vs Simple Custom CSS and JS