Nick Halsey

WordPress core provides custom CSS functionality in the customizer that’s specific to the current theme; you can switch themes freely with each theme’s additional CSS remaining in place. This is particularly useful on multisite networks, where it’s often impractical to use child themes to save customizations for each site. Unfortunately, custom CSS is not visible to site admins on multisite networks by default because they are not trusted with unfiltered CSS.
This plugin gives site admins access to the core custom CSS feature by mapping the <code>edit_css</code> capability to <code>edit_theme_options</code>, thereby trusting site admins with unfiltered CSS.

Multisite Custom CSS

Just as much code as it needs :)

Perfect

Nice!!!

WordPress core provides custom CSS functionality in the customizer that's specific to the current theme; you can switch themes freely with each t …

Andrew Norcross

Reaktiv

The Reaktiv CSS Builder allows site owners to add custom CSS for any part of the site directly in the dashboard. Unlike other CSS builders, this plugin creates an actual CSS file and loads that instead of putting it all in the head, allowing the file to be cached.
Features
<ul>
<li>CSS editor contains live syntax highlighting</li>
<li>Multisite compatible</li>
<li>Import and export capabilities</li>
</ul>

Reaktiv CSS Builder

Add user generated custom CSS directly in the dashboard.

Multisite Custom CSS vs Reaktiv CSS Builder