I'm just now diving into responsive CSS and design, and I'm wondering how I'm supposed to figure out various device widths out. I don't want to spend all day testing every single mobile device possible, I just want to get the responsive layout enough to where it works.
I saw some sites using @media only screen and (max-device-width: xx)
but it seems that limits it to very specific resolutions, not actual browser window sizes.
Any advice at all would be great. I'm not new to web development or CSS, but totally new to responsive design.