different sizing for radcombobox for mobile & desktop

I have a radcombobox in my page (using Skin="WebBlue").

The page has loaded with different css style based on if it is rendered on mobile or desktop(style.css & stylemobile.css)

Now what I want to do is set different size property for the radcombobox: Height,Width and DropDownWidth etc. How do I overwrite it with css in different file? or is there any better solution?

I used table in HeaderTemplate and ItemTemplate, is it possible to use different width for cells based on mobile/desktop?

Thanks.