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.

Maxaud

This plugin allows you to define different CSS rules that get loaded into the page’s for specific devices.
Includes checks for 18 different tablet options and 13 different phone options.
This can be useful if you need to target specific phones or tablets to make CSS changes or show certain advertisements for certain devices.
For more options or if you feel like donating, check out the <a href="http://codecanyon.net/item/mobile-css-pro/3182318/" title="Mobile CSS Pro" rel="nofollow ugc">PRO version of Mobile CSS</a> that is available for purchase.

Mobile CSS

Allows you to define different CSS styles that get loaded for specific mobile devices.

DBD Login Style vs Mobile CSS