Ari Stathopoulos

A clean, minimalistic administration theme inspired from the new customizer look of wordpress 3.4.1 
It’s pretty basic and adds a css file to your administration.
Since this plugin was created I have used the knowledge that I have acquired to build the bootstrap admin theme, which I would recomend you use instead of this one. 
You can get it here: https://wordpress.org/extend/plugins/bootstrap-admin/
This project was built for the http://magazi.org network of stores.

Magazi Admin Theme

A clean, minimalistic administration theme inspired from the new customizer look of wordpress 3.4.1

Scott Reilly

Ever want to tweak the appearance of the WordPress admin pages by hiding stuff, moving stuff around, changing fonts, colors, sizes, etc? Any modification you may want to do with CSS can easily be done via this plugin.
Using this plugin you’ll easily be able to define additional CSS (inline and/or files by URL) to be added to all administration pages. Hooks are provided to customize the output of the CSS, the CSS files, and if/when the CSS should even be output (see Hooks section).
Links: <a href="https://coffee2code.com/wp-plugins/add-admin-css/" rel="nofollow ugc">Plugin Homepage</a> | <a href="https://wordpress.org/plugins/add-admin-css/" rel="ugc">Plugin Directory Page</a> | <a href="https://github.com/coffee2code/add-admin-css/" rel="nofollow ugc">GitHub</a> | <a href="https://coffee2code.com" rel="nofollow ugc">Author Homepage</a>
<h3>Developer Documentation</h3>
Developer documentation can be found in <a href="https://github.com/coffee2code/add-admin-css/blob/master/DEVELOPER-DOCS.md" rel="nofollow ugc">DEVELOPER-DOCS.md</a>. That documentation covers the hooks provided by the plugin.
As an overview, these are the hooks provided by the plugin:
<ul>
<li><code>c2c_add_admin_css</code> : Filter to customize the CSS that should be added directly to the admin page head.</li>
<li><code>c2c_add_admin_css_files</code> : Filter to customize the list of CSS files to enqueue in the admin.</li>
<li><code>c2c_add_admin_css_disable_css</code> : Filter to customize if the CSS defined via this plugin should be output or not.</li>
</ul>

Add Admin CSS

This plugin did *exactly* what I wanted. A plugin had dropped some ad stuff into the Publish box, but it had a good CSS class, so I just hid it.

I really like that the text field for holding the CSS is intelligent and does things like auto include closing brackets, code coloring, etc.

Worked perfectly

Easily define additional CSS (inline and/or by URL) to be added to all administration pages.

Magazi Admin Theme vs Add Admin CSS