If you've watched any of the Omega Theme videos available on the Internet (see Jake Strawn (aka himerus) Introduction), you will hear the Omega Theme described as being built from 'mobile to desktop", instead of from desktop down to mobile. The basic idea is that the 'default style' of a website should be one that looks good on mobile devices and that stylesheets should change as the browser window's size is changed or pages are displayed on different sized devices. There are so many stylesheets associated with the Omega theme that I was easily overwhelmed and confused. This article attempts to describe how some of the various CSS stylesheets that are involved in that process are configured.
Starterkit CSS Files
After you've create a custom theme from the Omega base theme using one of the starterkit folders provided with the theme, you will find 5 files in your custom_theme/css folder. Most of these files are named after the starterkit you chose. The list below are those files included in the omega-html5 starterkit as of this writing: