On my sites, I'm using boost to allow much faster access time (close to instantaneous in comparison to hitting Drupal and all the database accesses...)

The result is great! But it generates some problems when you test a page. It does not get refreshed... Easy, you can clear the cache. Not advisable when your cache is around 10,000 files. A better way, is to go to that page and click on "Flush Page" (available in one of the blocks offered by boost.)

Now, this works for the page, but not the CSS. Also, if you are like me, you may be using many other modules that prevent you from using the "Flush Page" button... I use the "domain" module and I'm not logged in the right domain—let me rephrase that—I cannot log in the right domain to have access to the "Flush Page" button! This means I have to delete the files by hand (I go on the server and use rm <filename>.)

So... what about the compressed CSS? Easy! You have a file that's created by the system and it is saved under sites/default/files/css/*.* One file per page or something like that (I'm not too sure how that part works, but I always see many files in the folder.)

Thus, what I do is delete that CSS file. Then I hit Reload in my Browser and it does not work?! Why not? Because the page itself also needs to be refreshed! I have had that problem several times now. So what I do is this:

1. Go to the cache area, rm <page>.html*

2. Go to the CSS area, rm <css for that page>.css