CSS

A "sustainable" theme is one that can grow seemingly effortlessly as the site grows. It saves time reducing theme work in the long term, and allows developers to change and add new sections that just "look right" right away.
Agenda

Using the custom theme of a large website as an example, I will go over:

Fluid web designs have many benefits, but only if implemented correctly. With proper technique, a design can be seen correctly on large screens, small screens and even tiny PDA screens. With bad coding structure, however, a fluid layout can be disastrous. Because of this, we need to find ways to work around most, if not all, of the cons of fluid design.

This module solves the Internet Explorer limitation of loading not more then 30 CSS files per HTML page (http://support.microsoft.com/kb/262161). It is suitable for Drupal websites using lots of modules that can quickly increase the number of CSS files. The module doesn't require any configuration, just enable it and it will automatically change the way Drupal loads CSS files. It works well with built-in Drupal 6 CSS compression.
Acknowledgements

Based off of Javascript Aggregator this module will gzip your aggregated css files. For Drupal 6.x
Advantages

• It's compatible with Apache 1.3 (works great with cheap hosting).
• Compresses the content once and saves the result (less CPU load on server).
• Uses level 9 compression because it's only run once per file (smaller file size).
• In general, all you need to do is enable the module and it works (no core hacking/modifying .htaccess).

Disadvantages