On CSS optimization, SASS and CSS frameworks / resetters
IMHO CSS Frameworks and reset-files should not be used (for non-enterprise websites) as they only bloat the CSS files massively. And CSS parsing does cost performance as well.
You can add your CSS selectors in a compatible way so even IE6 looks similiar or the same. And if it does not, who cares? IE6 is dead, or should be. So enforce it!
Be part of good, standard compliant and minimalistic CSS files.
A good workflow, including SASS, is to use Ant on your CSS files for deployment. You develop with SASS CSS files and on save / compile / deploy your IDE should run the corresponding Ant-task (or other build-script) which calls a SASS parser to convert it to valid CSS, which in turn will be passed to a CSS minimalizer and/or obfuscater.
Voila, you have a readable SASS file for development, even allowing you to use variables for your CSS, and minified and minimalistic CSS files on your production system. Perfect!
(A test-system should use converted (SASS to) CSS files which are not minified or obfuscated obviously, for easy debugging on the page.)
Looking into merging CSS files may be good as well, depending on if you actually have more than one or very many.