dubhunter

WordPress’s themes are absolutly amazing, except you are not able to theme the login pages very well. 
DBD Login Style is a light weight plugin that will allow you full theme control over the login pages. 
It also offers additional DIV tag creation for custom messages.
Some Features:
<ul>
<li>Specify CSS style sheet for login pages.</li>
<li>Change the URL and TITLE of the header link.</li>
<li>Add specific messages to the different login pages (Login, Registration, Forgot Password)</li>
<li>Change various error messages on login and registration pages.</li>
</ul>

DBD Login Style

Add style to your login page!! This plugin enables you to specify a style sheet to be used on the login page.

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.

DBD Login Style vs Add Admin CSS