One way we work with our CSS on our mobile product is to use tools like Chrome's developer tools to override the user agent:
https://developers.google.com/chrome-developer-tools/docs/mobile-emulation#emulate-device-viewports
(See "Emulating the User Agent")
Once you refresh the page, you can then use Chrome's Developer Tools to inspect the elements you're interested in.
You can also force the device view of our product by adding "?device-view=mobile" to the URL like this:
http://h30434.www3.hp.com/t5/Android-Tablets-e-g-HP-Slate-7/bd-p/android?device-view=mobile
You can switch back to the desktop view by clicking "Full" in the footer of the mobile pages or adding "?device-view=desktop" to the URL. Hope that helps.