Updated CSS files with a hack to get the HD icons to display on 'retina' devices

I have not tested this on a "retina-display" of an iPhone (4[s],5) but my Galaxy Nexus GSM with Android 4.1.2 has a 315PPI display and with -webkit-min-device-pixel-ratio: 1.3 it is caught by the Media query. Needless to say, when using unmodified versions of this CSS, I cannot not for the life of me get my Nexus to display the HD icons.

I tried playing with the pixel ratios in the media queries with no success. I replaced it with my own Media query from a LESS CSS mixin I use which catches lower density displays that are just barely what you would call "retina".

This still didn't work so I busted out Remote Chrome Dev Tools using Chrome for Android on my phone and to my surprise, it was not actually using the background-image url of the HD icons, but actually using the SD version and still following the background-size of the Media query.

I added an !important to the HD set and presto! Now, I know adding !important is bad-form and frowned upon but in this case it is a hack that works for now without further investigation. This my first pull so please give me feedback!