When in the admin configuration form '{host}/admin/settings/performance' the option "Optimize CSS files:" is set to value "Enabled", the module 'modules\system\' should combine/ minify (http://en.wikipedia.org/wiki/Minification_%28programming%29) all stylesheets into a single (!) stylesheet.
However, in aforementioned case (and while non-core modules which generate stylesheets are disabled), still TWO stylesheets are generated (each with different Etags in the headers of the HTTP-response).
The uncombined stylesheets are:

  • modules/node/node.css
  • modules/system/admin.css
  • modules/system/defaults.css
  • modules/system/system-menus.css
  • modules/system/system.css
  • modules/user/user.css
  • files/color/garland-xxxxxxxx/style.css
  • themes/garland/print.css

Quote from http://developer.yahoo.com/performance/rules.html#num_http:

Decreasing the number of components on a page reduces the number of HTTP requests required to render the page, resulting in faster page loads. Some ways to reduce the number of components include: ... combine multiple CSS files into one style sheet ...

PS: To check the number of components of stylesheets, I read the cells in the column "TYPE" on the tab "Components" of the Firefox add-on YSlow (https://addons.mozilla.org/en-US/firefox/addon/5369).

Comments

damien tournoud’s picture

damien tournoud commented
Status: Active » Closed (won't fix)

Nobody said that every stylesheet should be combined. On the contrary, stylesheets that are not used on every page should not be combined, because it would increase the number of aggregated stylesheets, resulting in more data needed to be transmitted from the server to the client.

Please reopen if you have *specific* reasons to think one stylesheet preprocessed while it is not.

not_Dries_Buytaert’s picture

not_Dries_Buytaert commented

So, the system is intentionally designed to NOT combine and to serve multiple stylesheets which are not used on every webpage, even when earlier mentioned option is enabled. Thanks for clarifying this.