Media query to target desktop only?

I am using an Omega sub theme on this site: http://95.138.187.151

I am using the style sheets at default breakpoints to get the layout working nicely for different devices, but when I shrink the browser to emulate smartphone size some of my mobile rules aren't working. Specifically, you can see the title on the carousel drop down beneath it and the controls dissapear.

I have all the mobile stuff set in global.css in these two media queries and it's working just as I would want it to on mobile devices.

@media only screen
and (min-device-width : 320px)
and (max-device-width : 568px)
and (orientation : portrait)

and

@media only screen
and (min-device-width : 320px)
and (max-device-width : 568px)
and (orientation : landscape)

I tried adding some styles in a media query like this in the hope that not specifying portrait and/or landscape might have it not be picked up on mobile, but alas it overrides what's in the query above:

@media only screen
and (min-width:320px)
and (max-width:568px)

I also tried changing the breakpoints in [theme].info to stop the mobile styles kicking in at a greater width on desktop, but to no avail.

To be honest I'd be happy if the styles in [theme]-alpha-narrow just remained on the desktop site no matter how small you shrink the browser and have the top two media queries above only kick in on mobile. Can anyone see where I'm going wrong? I'd prefer the site to not look such a mess if users on bigger monitors decide to shrink the site down etc...

Basically I just wanted to know if there was a media query I could use that would only affect desktop devices...?

Thanks in advance!

Rob.