Jesse Friedman

One of the hardest parts of building Responsive WordPress themes is maintaining responsive integrity after the site goes live. User Admins can have limited coding abilities which can prevent them from maintaining responsiveness in themes.
WP Mobile Detect aims to make it extremely easy for anyone to wrap content in the editor with shortcodes which will hide content based on visitor device at the server level.
No longer do we need to rely on display:none; or other techniques to hide content for mobile devices. Instead we can replace content with alternatives. When a full-size infographic in your post is unknowingly displayed on a visitors phone we can consider that an Non-user initiated download. In other words that visitor had no idea what they were getting into and you possibly just choked their bandwidth.
WP Mobile detect gives you the ability to wrap that infographic in a [notdevice][/notdevice] shortcode so at the server level WordPress will decide to show that content only if the user is NOT on a phone or tablet. Alternatively you can wrap a link and corresponding text to that info graphic in a [device][/device] shortcode as a way for the visitor to consume that content if they so choose.
This plugin is based on the <a href="http://code.google.com/p/php-mobile-detect/" rel="nofollow ugc">PHP Mobile Detect class</a> 
WordPress Plugin written by <a href="http://jes.se.com" rel="nofollow ugc">Jesse Friedman</a>

WP Mobile Detect

WP Mobile Detect by Jesse Friedman creates an easy way for the User Admin to control when content is shown or hid based on visitor device or operating …

qstudio

Easily include browser specific stylesheets in templates or select browser and version specific classes in CSS.
Conditional browser stylesheets are added after the main theme style.css allowing them to overrule previous rules – you only need to add the CSS rules that should change.
This plugin uses up-to-date WordPress top level functions, sanitizes all input data and is fully internationalized.
For feature request and bug reports, <a href="https://qstudio.us/support/categories/conditional-stylesheets-and-body-classes" rel="nofollow ugc">please use the Q Support Website</a>.
Please do not use the WordPress.org forum to report bugs, as we no longer monitor or respond to questions there.
<h4>Features</h4>
<ul>
<li>Checks for and adds browser and version specific stylesheets – such as “browsers-windows-firefox.css”.</li>
<li>Add browser and version specific body classes to all pages – such as body.browsers-msie-10</li>
<li>Includes the Mobile Detect class and adds mobile & touch body classes.</li>
<li>Adds a post type body class, for example: “posttype-page”.</li>
<li>Inserts handy HTML comments in the HTML footer of template files to tell you which CSS files could be used and which were found.</li>
</ul>

Conditional Stylesheets and Body Classes

Add conditional browser stylesheets and body class declarations

WP Mobile Detect vs Conditional Stylesheets and Body Classes