I only started using CSS based layout when I started using drupal. After a few tutorials I new basically how things worked, but when it come to learning and modifying drupal themes I found things a little more difficult. Every theme’s css file is laid out differently and things are grouped differently.
I think it would be good idea to set a standard for the layout and grouping of CSS in style sheets files using comments.
I have tried multiple themes and every time I try to modify a theme I have to learn how that Theme Developer layout and grouped elements in that theme and it is completely different form theme to theme. How one person thinks things should be logically grouped is not at all logical for another user.
What I propose is a basic layout of drupal theme css files. IE. All HTML elements at the top, followed by, all page layout elements group together and then all CSS relating to comments ….. And at the end theme specific CSS. (Just a example)
I think this could promote Theme development. This way a person only needs to learn one structure. And will know more or lees how things are laid out for any theme, making modifying exiting themes much easier. And maybe reduce the drupal learning curve for new comers and CSS novices.
And in the download area. The theme description should specify if it conforms to the standard just like some of the themes specify that it is a PHPTemplate theme.